Because of the blizzards that hit the Twin Cities over the last day, the Vikings-Giants game has been postponed and moved to Monday night.
The NFL hasn't scheduled a time yet, but I would guess it would be some time around 8:30 PM, the time of the normal Monday Night broadcast.
The Giants were stuck in Kansas City and couldn't get into Minneapolis, as 15 inches of snow shut the airport and they wouldn't be able to fly out until Sunday morning. And apparently there was a leak in the Metrodome roof as well, so that made the decision to postpone a lot easier. Here's more from NFL.com.