I will call this a minor bug, since not being able to play your music for 24 hours is going to be just an annoyance. However, the fact that early generation Zune cannot handle leap year is shambolic from a technical viewpoint.
Why? It is not something that is unexpected. We know it happens every four years since a extremely long time ago. Unless you are creating something one-off that you do not expect to last to the next leap year, you have to deal with it. Nobody in their sensible mind will think that early generation Zune buyer will discard their device before the next leap year.
Will Microsoft fix it with the next driver update? I hope so. However, the technician in me says that this is a bug not worth fixing. First, it affects only early generation Zune. Quite frankly, by the time we reach the next leap year, those devices would had been about 5 years old. Knowning how people use music devices, and the fact that at that time, the cost of replacing the original battery could probably outweigh the benefit of keeping those device running, there is not going to be a lot of them around by that time.
The benefit of fixing a bug must be considered against the cost of fixing it. Ironically, I think from a purely technical standpoint, the rational mind will say it is debatable whether it should be fixed.
Thus, those of you with a early generation Zune that plans to use it in 2012 should make a note of the problem. Write it in your diary NOW! 😉