About 20 minutes ago I got my invite to google wave. I now have my account live (brooke@wavesandbox.com) as well as my secondary account (brooke-test@wavesandbox.com), so I can start testing out the wave. I haven’t had any time to get into it and play, but here is a screenshot of an empty preview account 
Update:
After about 20 minutes, everyone started using wave and this is what it looks like
Update 2:
When I tried to reply to a wave that was created after I first loaded the page.
Looks interesting. I want an invite!