Spent a couple hours yesterday, playing with Google's Wave in a Box (WiaB). The install was very smooth, though it did take a little over 11 minutes for ant to wade through the various .jar's and build the server.
If you're building your own WiaB and get a lot of "cannot connect" errors, take a look at what interface your server is listening on (i.e., use netstat). Even though I'd properly configured the forward and reverse lookups in DNS, I'd forgotten that Linux is usually configured to check /etc/hosts first. Since I'd left the `hostname` code in the config file (where "hostname" is surrounded by backticks), it was actually defaulting to "localhost" vice the proper IP address for the server. (Note: you probably won't receive this error unless you're running WiaB and your XMPP server on different systems.)
Experimenting with federation took a bit longer as it requires configuration of DNS, /etc/hosts, and SSL certificates. Nothing too difficult though. End result is that I now have a WiaB instance tied to the Openfire server. Notes in the wiki shortly.