NASA engineers are trying to make sure the Shuttle isn't in orbit on December 31st. The reason? They've never (in 20+ years of flight) had the thing in orbit when the year changed, and they're not sure what the computers would do. Seems to me you'd just light up one on the ground and keep ticking its calendar forward until it happened, but something tells me that in the Shuttle it's way more complicated than that. With the Shuttle, it usually is.