YouOS

The conversation went like this:

Dom: It's all about Camino, man.
Jeremy: Is it fast? How is the Javascript?
Dom: It rocks Gmail.
Jeremy: Bring up YouOS.
Dom: Woah. Shell script. Chat. FlickRSS.
Jeremy: Yeah, chat with the dudes, they're cool.

20 minutes later, I'm still in YouOS.
And yeah, the guys are cool.

Their designer is on a Mac.