There are at least two Grails plugins that emulate the database migration functionality of Rails:
Is there a consensus a
At least as of Grails2.0, the database migration plugin is the defacto way to handle non-trivial database changes. The plugin is built on Liquibase, and is authored by the Springsource folks - always a mark of quality. I wrote an introduction to the database migration plugin which might be of use to someone reading this.