Robert Cooper has posted a discussion on Groovy and Grails in the O'Reilly Opinion section.
A lot of Groovy people are (rightly so) pissed — can I use that word here? — that Sun effectively "endorsed" Ruby over Groovy. Grails is an .... almost... perfectly good analogue to Rails, and Groovy definitely sits better with most Java people.
Here is the problem, guys. You aren't buzzword compliant. At this point, arguing the merits of Groovy over Ruby or Grails vs Rails doesn't matter in the least. The "technorati" have dubbed RoR "the big thing."
http://www.oreillynet.com/onjava/blog/2007/02/dear_groovy_people.html