I've been running Longhorn since July 2006. I upgraded to RC1 a few months back, since then at times I forget about my IISLogs.com server. This is pretty much an appliance at the time of posting the uptime is 33 days. Ok... it is not months or years however for a beta OS with no restarts and serving about 3000 users a week, this is pretty good I think. The IIS7 adventure continues...
Here is a picture of the uptime. I thought this was worth sharing.

Tx,
Steve Schofield
Microsoft MVP - IIS