Before I start talking about using Groovy's capabilities to create a DSL (mostly in Java), let's take a few minutes to go over what Groovy is.
Groovy is a general purpose scripting language which runs on the JVM, and can largely be viewed as a superset of Java.
I've been neglecting my blog, but just a quick note to mention that my latest talk at JavaOne, DSLs with Groovy, is posted up on Slideshare.
The talk's designed for someone with no significant Groovy experience (unlike most Groovy DSL talks), so if it's interesting to you, check it out.
I'm hoping (but not promising) to turn the talk into a series of Blog entries in the coming weeks.