Jan 31 2009: ruby-lang.org has released the first production version of Ruby 1.9, some bugs and problems with gems, also see Ruby 1.9.1 Released - Fastest Ruby Ever.
Updated Dec 14 2008: link for Ruby Shootout.

Some useful links.

Jan 31 2009, added EasyEclipse for Python IDE
Dec 13 20008: A few preliminary links ... and two new links on the Great Self Debate !

A Minor Harangue

I remember a time not so very long ago when I was required to spend an afternoon adding "^yourself " to the end of several hundred Smalltalk methods because "that's the right way to do it". I predict that the use of self in Python method arguments will persist for much the same reason.

March 19 2009: Squeakland-EToys updated, see the EToys download page.
Updated July 10 2008: Pharo - new, leaner fork of Squeak. See related link.

From Wikipedia on Squeak Smalltalk:

Feb 3 2009: reflections on the power of modern marketing in selecting rule engines.

Sun appears to be serious about open sourcing the Java Development Kit and Virtual Machine, so it is time to consider Java as an environment for implementing Open Source rule and inference engines.

As an interpreted language, the performance and resource consumption of client and server-side solutions will probably be a critical design factor, particularly as Java-based rule engines tend to aspire to enterprise-level applications.

From the site:

FDSE is an easy-to-install search engine for local and remote sites. It returns fast, accurate results from a template-driven architecture.

Drools is probably the leading Open Source Java rule engine and rule management environment. It is the community version of commercial JBoss Rules. The whole operation os very solid - the Drools/JBoss Rules User Guide is among the best of any business rules product, either open source or commercial.

The following is a heavily paraphrased version of the three main points on Drools site:

Updated: Sept 24 2008: more links, RAP

A very thin category at the moment, but the new Drupal Rules project may help to fill it out.

The RAP project has a simple forward and backward chaining inference engine using networks of relationships rather than condition/action statements like a true rule engine.

Updated: June 20 2008

Galaxia is an activity-based workflow application, where the processes and the workflows are made of dynamic activities that must be completed to finish a task. Contrast this with a procedural system where each step in the process must be completed in order, and the power of this application becomes clear.

Potential RDF use cases for Drupal - an excellent article about RDF in Drupal 6 - 7.

The Drupal RDF module uses the recently-rewritten ARC2 RDF Library if available but apparently does not require it.

Update 3/26/2008 - ARC completely reimplemented and released as ARC2.

Update 7/25/2008 - added Triplify 0.3 section.

From the ARC site:

ARC is a lightweight, SPARQL-enabled RDF system for mainstream Web projects. It is written in PHP and has been optimized for shared (or otherwise performance- or privilege-limited) Web environments.

ARC facilitates the integration of RDF and SPARQL functionality in PHP/MySQL-driven frameworks.

Browse PHP Debug package

PHP Debug - PEAR

Nice documentation front end, Good use of AJAX. Dual licensing.

• Demo of documentation for Ext version 1.1, powered by Ext 1.1.
• Demo of documentation for Ext version 2.0-dev, powered by Ext 2.0.

OntoGrid provides a technical infrastructure for the rapid prototyping and development of knowledge-intensive services for the Semantic Grid.

From the site: "This prolog is enhanced with the JavaScript callout capability though a rudimentary external/3 call; see the arithmetic functions for examples".

A link to History.

Updated Sept 19 2008:

From the article "Using Prolog as the fundament for applications on the semantic web":