I don't think Grails was much alive (in terms of adoption) at any point in time.
It is as it ever was, there is even a new version out.
You'd be mostly on your own + SpringSource, though, don't expect a Rails/Django sized community, or even a Sinatra or CakePHP sized one...
Groovy itself, the component language, has also lost a lot of core developers and momentum, especially the project lead at most of the language's development:
"In July 2009, Strachan wrote on his blog that "I can honestly say if someone had shown me the Programming in Scala book by Martin Odersky, Lex Spoon & Bill Venners back in 2003 I'd probably have never created Groovy."[1] Strachan left the project silently a year before the Groovy 1.0 release in 2007."