I think that a technological threshold has been reached and that rules technology is no longer the the sole domain of large-scale business processes. It can be made easy enough and powerful enough to support simple problem solving by ordinary, non-technical individuals.   With the advent of inexpensive web hosting services and web-logging technology, a combination of workstation and server side functions can implement a sort of personal knowledge server.  The critical factor is to create an the interface that is simply enough for everyday, non-techie to understand and use.  

Furthermore, I believe that the technology can adapted to a vision of the Semantic Web.  However, developing a rule systems technology for a Semantic Web may require significant modifications and extensions to existing concepts and tools.  In fact, it is not clear what the term 'Semantic Web' means and the challenge of resolving competing visions and definitions is taken up in a later section covering the Semantic Web. 

That invaluable tool, the Wikipedia, has the cleanest and concise definition of the term 'business rule' I've encountered.  The Wikipedia defines business rule as:

Declarative: A business rule is a statement of truth about an organization. It is an attempt to describe the operations of an organization, not an attempt to prescribe how an organization should operate. This is why business rules are said to be discovered or observed and not created. 

Atomic: A rule is either completely true or completely false; there are no shades of gray. For example a rule for an airline that states passengers may upgrade to first class round-trip tickets if seats are available and they pay the fare increase does not imply that this deal is available for just one leg of the journey.

Distinct, independent constructs: Separate the things that define your business (the rules) from the processes (i.e. strategies and tactics). Don't build complex and cyclical dependencies - simplify and flatten the constructs.

Expressed in natural language: In order to appeal to the broadest audience, it is almost always best to express business rules in a natural language without the use of a lot of technical jargon.

Business, not technology, oriented: For example, a company's business rules should not be foreign to a knowledgeable customer. 

Business, not technology, owned: Business rules come from business decisions. These are independent from implementation decisions.

There are many definitions of the term "business rule".  Some focus on the high-level idea of business "policies", delineating how the company will do business.  Business policies are distinct from procedural knowledge about business operations and often seem to be arbitrary, such as a policy to send a customer debt to a collections agency after 60 days.  Why not 75 days or 45 days ?  It is purely a policy.   

Haley has an interesting take on the definition of business rule.

Business rule :is a statement that defines or constrains some aspect of the business.  A business rule asserts business structure to control or influence the behavior of the business, i.e. a process or procedure.

Note that the definition treats procedures as a legitimate expression of knowledge about a business process of some sort.  In the field of Business Process Modeling, the sequence of operations in a business processes can become something like a business rule in itself.

It is an import distinction and the correct view, a process-based or rule-based point of view, depends largely on the category and level of interaction of the business rule under consideration.

Business rules tend to appear at the enterprise level.  Processes tend to use business rules in a 'localized' way, for instance by geographic location or by market segment.  A certain set of business rules can play a role in some aspect or 'facet' of a particular business process.  They might even be categorized along several dimensions simultaneously, for instance by geographic location and by market segment at the same time.

The demands of large globalized business applications can generate massive numbers of "localized" rules by combinatorial explosion of 'sub-types', sometimes many thousands of individual categories of business rules.  In those situations, a bottom-up, process-based approach to business rules analysis can be very effective.           

Note first that there is a big difference between The Semantic Web to A Semantic Web.  In this version of the Semantic Web, knowledge shared by individuals.  A web would be owned by its participants or subscribers rather the general public, something to be actively joined, perhaps more like the basic model of a Wiki  than an openly accessible public site.         

If there were a version of business rules called "semantic web rules", what would its definition look like ?  Certainly, the definition should include a very basic set of characteristics pertaining to the Semantic Web.  It would also need to stay as close as possible to the classic definition of business rules or there is a danger that the entire meaning and "discipline" of the methodology could be lost. 

Owed by Originators and  Stakeholders – Web rules are owned by their originators of the knowledge, rather than by casual users or a technically oriented cadre of web developers.

Knowledge Focused – Web rules should describe common knowledge-intensive problems and issues encountered on the Web and their resolution.

Unique – Web rules refer to a single subject at one time.

Clear and Unambiguous – Web rules make a clear statement of things known about the Web and uses a well-defined terminology.

Declarative – Web rules make assertions about things important to understanding and using available resources. Note that in many definition of business rules, declarative mans that they do not describe sequential knowledge or processing logic.

Well-Formed – Web rules are stated in a formal rule language.

The last three requirements for business rules may raise an important issue for using business rule technology in the Semantic Web. 

Note that the last three characteristics listed above ( that is, clear, declarative and well-formed ) may restrict the form that web rules can take. To some extent, they may also limit the usefulness of classic business rules as a vehicle for defining things in the relatively unstructured environment of the Semantic Web.

The central question is, how realistic are these requirements outside of the limited, well-defined domain of business transactions ?  In well-defined domains such as making bank deposits or processing customer orders, a rule can be either "completely true or completely false", but how often is that true in real life.

Another question is, to what extent "clear" and "well-formed" rule can be utilized by individuals in confronting the incomplete and contradictory information of every day life, such as those requiring someone to spend three hours on the phone attempting to correct the consequences of erratic business policies and information systems.

Some web rules will not be "well-formed" enough to be expressed within the confines of a restricted and specialized computer-friendly rules language. They may be difficult to express and not every rule 'owner' in the web community will be interested in learning a new language to express their rules. More likely, they will think in terms of everyday language and they may not be willing or able to translate their knowledge into a formal rule language.

What we are seeking is rules that are not necessarily "well-formed" but are  "adequately-formed" enough for the more rough and tumble world of the Web, where the quality of the rules themselves are likely to be less controlled and less reliable than in a classical big company environment.

The most immediate goal is to capture knowledge about the Semantic Web in whatever form it present itself, even if encountered in a contradictory form.  It is assumed, in a tentative way, that discovery of web rules will be very similar to rule discovery in a business context, even if the content of the rules is very different.  The basic "laws" of analysis and discovery ( via logic induction, for example ) will be be valid within a semantic web the same as any classical business rule domain.  In fact, the relatively simply, people-oriented user interfaces developed by 20-year-old business rules technology may even have something to teach 20-year-old Semantic Web developers.  ;-)  

After discovering relevant business rules, the rule analyst need to transform their natural language descriptions into "well-formed" statements that can be used to satisfy the demands of a  knowledge-intensive task.  And that requires a business rules methodology.