I've got severn, the latest Red Hat beta, up and running. My first impression is that they've done something to improve UI responsiveness. Maybe that's not the case and my old install was slower for some other reason but this just feels a bit quicker. I'm having difficulties with the package manager and automounting CDs. There's not a lot that sticks out as being new but I've only been on it for a day so maybe I'll find more as I go.
Today we have new (maybe final?) candidate builds of Firebird 0.6.1. You can help us out by testing builds from firebird ftp and reporting any problems in the comments here or over at the mozillazine discussion thread.