Good news: It's in the app store, works with Lion (10.7), lots of new features and support for GNTP
Bad news: It's in the app store (for $1.99), you MUST have Lion to use it.
It's easy enough functionality, when you're only supporting one app, and I don't want functionality for my-users to depend on a paid app they may not have.
Adium was a big driver for Growl adoption. It'll be interesting to see what they do.