I just had a surprise reply from Dmitriy Demerov of JetBrains:
The latest Early Access Preview builds of Diana (available at http://www.jetbrains.net/confluence/display/IDEADEV/Diana+EAP ) include a plugin for Guice support. You're very much welcome to give it a try and submit your feedback on it.
I had responded to a sales manager at JetBrains that one item on my wish list for IDEA was direct Guice support.
Yippee!
