Apache Google Wave in a Box project is starting to look good
It has been a long time since I tried to run the wave protocol stuff. I just grabbed the latest source and followed these directions on my MacBook. I was quickly up and running with no problems.
The web UI is a lot simpler than Wave but looks similar. Wave in a Box is looking good as a development platform - something to customize for your organization.
I used two browsers, Chrome and Safari to create two test accounts, and as I expected, the real time messaging, etc. worked fine.