Thanks to the Google Summer of Code programme, we have Lucas Amador working on refactoring support for rules.
Initially the focus is on the Eclipse plug in (of course) – as Eclipse has excellent support for refactoring tools that are not java source specific – but the intent is to have the feature available to other tools (such as Guvnor, or perhaps other IDEs in future) for bulk refactoring.
More info is on the wiki page here.
Lucas also made a video demonstrating some of the enhancements here:
GSoC 2009 – Drools Refactoring from Lucas A. on Vimeo.
For those really really interested, and crazy, the code as a work in progress is available from here.