RDT is an open source Ruby IDE for the Eclipse platform.
Features supported are syntax highlighting, on the fly syntax check, graphical outline, Test::Unit view/runner, Ruby application launching, content assist, source formatter, Ruby debugging, Type Hierarchy view, Ruby specific Search, Refactoring, and much, much more.
A regular expression plugin is also available (Thanks to the EPIC project).

Once again, I've been a bit lax about updating this site. For those who haven't heard, Aptana has hired me full-time to work on RDT and RadRails.

As a result, much of the project will be migrating over to Aptana's site and infrastructure. One of those is our Trac site. We've already moved over to using http://www.aptana.com/trac as the new Trac site for RDT and RadRails combined. This should hopefully be our last move of Trac.

You can also keep up with general Aptana updates as well as RDT and RadRails specific news on the Aptana blog.

Sorry, we've been pretty lax in updating our Sourceforge site and as a result a number of people have gotten the impression the project is dead.

We're not dead!

We've migrated to using a Trac site for both our Wiki and bug tracking. You can find it at http://rubyeclipse.mktec.com/cgi-bin/trac.py/wiki

Also, you can always subscribe to my blog, Late to the Party, for personal updates on RDT related work (among other topics like Ruby and Rails).

Lastly, I'd like to make a very belated announcement here that we have two projects going on with students working on RDT. The first is ongoing work by Swiss students on bringing code generation and refactoring to RDT. They've already finished phase one and have a modified version of RDT available for download. We're working with them to merge their changes into RDT's trunk (and JRuby).

Also we have a project accepted for Google's Summer of Code. Jason Morrison is doing work on type inferrence for Ruby and we're integrating that with RDT. We've already had some success in doing some initial groundwork such as Marking occurrences of variables.