Martin Adamek who works on the Java EE NetBeans team is working on a new plug-in for Groovy for the next release of NetBeans. You can read more about the plug-in in his blog. I am pretty excited about this because Martin has a lot of experience with NetBeans development so I am sure we'll get good support for Groovy and Grails in the upcoming release of NetBeans. The scope of the plug-in is bigger than what Geertjan has been working on - including fully featured editor with code completion and so on. I confirm that even though this is a new plug-in different from Geertjan's, Martin and Geertjan are friends, I've seen the meeting in our office :)
We started to use the slogan "NetBeans is the only IDE you need", but many developers asked us: "Where's good Groovy support?". So now I can say it's coming soon!