#rails-contrib is a new IRC channel on freenode for contributors to Rails. The Rails core team will hang out there to answer questions, discuss patches, and generally interact with anyone doing implementation work for the Rails framework. It's not meant for general chatter, though. Or for how to use the framework. It's strictly for implementational issues and the contributors working on those.
rubyonrails-stacks is a new forum to discuss how we can get standardized set of images going for Rails that can be deployed on any Xen host or even EC2. I posted a welcome with more details on the forum.