Groovy is to Grails, as X is to Y ?

Consider the following: Groovy is to Grails, as X is to Y.

I recently tweeted "... as C is to Unix". Though Mario quite rightly pointed out that much of Grails is written in Java, my thinking is that both Groovy and C enjoy greater popularity because of the success of their sibling application/system. i.e. It seems that Grails, as Unix once did, acted as a driving force beyond that of pure language development, which propels innovation and gives focus to an emergent style.

Dave Klein has his own tasty analogy about butter and pancakes.

And you? What are your values for X and Y ?

Ruby fans are invited to play the same game, with respect to Rails. Are there any values for X and Y which resonate for Ruby/Rails but not for Groovy/Grails (or vice-versa)? That one is very interesting.