Google Lively
Yes, it's here, yes it's a bit like Second Life, but it runs in your browser (assuming you're running Windows, but it's from Google, so it can't be evil).
Go grab the Lively plug-in and create your own room, or hang out in mine:
Nice, relaxing, calm - oh and did I say it works in your browser? So it should work through most firewalls - although you still need to be able to install it - so it's not quite going to be the next big thing for all your online corporate marketing and meeting needs, but I'm sure we'll try won't we?