I were curious to give grails a try - but were surprised to see it's not yet supported by gentoo. I'd be happy to see grails included in portage. Reproducible: Always
One of my main long term goals is to package Grails. But dont get your hopes too high - doing so well is extremely difficult. We would need to first package Spring, and lots of other dependencies. So it's very unlikely Grails will be available soon on Gentoo. However, dont let this put you down, you can just install it "the normal way" via the binary, and it works perfectly well (I use it everyday, and the framework is great).