Norway definitely didn't play up to expectations against Scotland and will have to be significantly better to beat Jamaica. That said - Norway always manages to get up for games that have big crowds, a high-profile opponent and are on TV. That's a 3 for 3 formula on Saturday night.
What Jamaica can do is score goals and run fast. To beat them Norway is going to have to play some suffocating defense and counter-attack effectively. Jamaica's defensive game is always a little suspect and their keeper is nothing special so good shots from far out should do the trick. Missing easy chances (like what happened against Scotland) will mean a Norway loss.
I'm optimistic about this game because of past success (4-2 semifinal victory in 2007) and the way that Norway is capable of shutting down fast, but not overly skilled teams. Norway plays a ball possession game and its likely Jamaica will get frustrated and leave itself vulnerable at the back.
I'm predicting a 5-2 win for Norway.