Judging by my inbox, there's truth to the story that 30GB Zunes are failing big style.
The problem seems to be date related and affects the latest firmware. There's rumors of a fix which involved removing the battery but a couple of 30GB Zune owners have told me this doesn't work, so in the meantime I'd advise against doing anything that might void your warranty.
For now, if you're affected I'd hold back and see what Microsoft comes up with.
[UPDATE: Zune Insider has an update on the situation (thanks Coffeeshark!):
Early this morning we were alerted by our customers that there was a widespread issue affecting our 2006 model Zune 30GB devices (a large number of which are still actively being used). The technical team jumped on the problem immediately and isolated the issue: a bug in the internal clock driver related to the way the device handles a leap year.
The issue should be resolved over the next 24 hours as the time change moves to January 1, 2009. We expect the internal clock on the Zune 30GB devices will automatically reset tomorrow (noon, GMT). By tomorrow you should allow the battery to fully run out of power before the unit can restart successfully then simply ensure that your device is recharged, then turn it back on. If you’re a Zune Pass subscriber, you may need to sync your device with your PC to refresh the rights to the subscription content you have downloaded to your device.
Customers can continue to stay informed via the support page on zune.net (zune.net/support). We know this has been a big inconvenience to our customers and we are sorry for that, and want to thank them for their patience. Q: Why is this issue isolated to the Zune 30 device? It is a bug in a driver for a part that is only used in the Zune 30 device. Q: What fixes or patches are you putting in place to resolve this situation? This situation should remedy itself over the next 24 hours as the time flips to January 1st. Q: What’s the timeline on a fix? The issue Zune 30GB customers are experiencing today will self resolve as time changes to January 1. Q: Why did this occur at precisely 12:01 a.m. on December 31, 2008? There is a bug in the internal clock driver causing the 30GB device to improperly handle the last day of a leap year. Q: What is Zune doing to fix this issue? The issue should resolve itself. Q: Are you sure that this won’t happen to all 80, 120 or other flash devices? This issue is related to a part that is only used in Zune 30 devices. Q: How many 30GB Zune devices are affected? How many Zune 30GB devices were sold? All 30GB devices are potentially affected.]