I have another (possibly premature) question about the multiple edition plug-in licensing...
Q: Now that is an open source version of IDEA, how will plug-in licensing and distribution work?
Related questions: Will Open Source edition users see the same 3rd party plug-ins listed in the available plug-ins as users of the Ultimate edition? In the future, will there be a way to distinguish in the IDE between those plug-ins licensed as open source and those licensed as commercial/closed source? Is it likely individual JetBrains' Ultimate edition plug-ins will be available (for a fee) to open source users?
Personally, I think this is a great way to get developers to commit to doing plug-in development for IDEA. While IDEA has always had a great developer community, many developers may have shyed away from developing plug-ins for it; "Why donate time and resources to develop a plug-in that benefits some company's commercial IDE?"
On the other hand, once plug-in skills have been mastered, it would be nice if there would be a way to monetize plug-in development efforts. (Ironically, many of the same people who insist on using only free software and tools still want to be paid for their own development efforts.)
I think this all could lead to a much more robust IDEA plug-in market. Frankly, I think the availability of so many plug-ins has been the 2nd biggest selling point of Eclipse. (The first being its price!)
JetBrains should adopt Apple iPhone's marketing slogan, "Need x? There's a plug-in for that."