That’s midnight Greenwich time, or 7am Eastern. ZuneInsider just twittered the following updates:
ZuneInsider: ok all. the issue is a bug in the driver that controls the internal clock. turns out it does not like leap years.
ZuneInsider: as the date flips to 09 the device should be back to normal. let the battery die the plug [...]

I’m getting quasi-regular updates from the Zune team at Microsoft, and they are applying a full-court press on resolving this issue.
Meanwhile, our forums are humming with reports from owners of Zune 30GBs about their players being frozen at the start-up screen.
For you all, here is some reassurance based on my read of the situation:
The problem [...]