A new version of the Groovy Eclipse plug is available (Version 18.104.22.168801232227) the update site is: http://dist.codehaus.org/groovy/distributions/update
I just installed it, it is definitely worth upgrading, it contains several new features that make the plugin more usable and closer to what you would expect (JDT). It also contains several bug fixes there were a little annoying.
A Couple of the more noticable enhancements:
- Support of java doc /*
- Code completion improvements Ctrl-space
- Quick Outline Ctrl-O
- Project Explorer shows groovy methods
(Not working in my environment)