Joomla Bamboo have released their own site theme this month to club members.
It wasn't described to me as a Web 2.0 feel but it has got that. The focus is very much on the content but the design is right there for all to see.
The theme has 15 module positions, uses mootools, is XHTML and CSS valid and 100% tableless. All in all a very nice look and feel.
For more information, a demo or to join the club click here.