The JavaPosse discussed Maven quite a bit in recent podcast #217. The consensus was that it's very restrictive in how it allows you to structure your projects, but that its usage is growing, and that it may offer a cross-IDE standard for representing a project.
Update—Javaposse also hosted an informative session at last spring's Java Roundup 09 entitled, "Maven with Pain?" I laughed (in horrified sympathy) as, toward the end of the recording, one of the participants related how a plugin update broke their build—two days before a production release.
I've steered clear of it, honestly, in large part because I find the name irritating. However, the ability to manage dependencies of third-party libraries is appealing.
Update—for those that have an irrational disdain for my irrational opinion, let me show you what "maven" conjures up in my mind:
Yes, in my mind, Edna Mode is the epitome of "maven". And I don't want her in my build—too bossy!
What would be a better name? Invented words are best for their pin-point Google results. For a good impression, root them in real words with a positive connotation.