I propose we could simply use the seemingly dormant Packages mailing list.
Since Universes are indeed collections of packages this would seem 
appropriate.

The last meaningful post in this mailing list was in Dec 2005.

To subscribe: http://lists.squeakfoundation.org/mailman/listinfo/packages

Prefix messages with the [development] universe to which you are referring.

best regards

Keith

p.s. now we just need to ask Lex to open things up a bit.