FWIW, almost everything we are doing at Fogbeam is Groovy (and Grails) based. I will agree that Groovy isn't as "trendy" as it was a couple of years ago, but it still seems to be progressing, and it's worked amazingly well for us. Personally, I'm a huge fan of both Groovy and Grails.
Back in 2009, Grails was the big theme in many JUGs in Germany.
We even added Groovy support to our JSF internal SDK as a means to buy into the "has Groovy support" checklist.
Nowadays, if it wasn't for Graddle, I guess it would be just maintenance related projects. At least from what I see as JUG talks.