GameTrailers has a nice preview of Mario Kart Wii up and running. It would seem there are a few things that will be quite different from past entries. Not a lot of things, mind you, and I suppose they aren't really that big of a deal when you think about it.... Anyways, one thing that is certainly different is how one power slides. Gone are the days where one could theoretically power slide throughout the duration of the race. Now there is a button you press to charge up your turbo to get a power slide and you let go once the meter is full for a speed boost. If that is too much for you to handle, you can have the game do it for you automatically (I am curious as to how that will work). Alternatively, there are things like half-pipes where you can perform tricks to get a power boost. That might be pretty fun.
Another thing that is different is the Battle Mode. When you lose all three of your ballons, you can keep on playing. The reason for this is because Battle Mode is now points based. I don't know how I feel about that, but I suppose I'll have my hands on it soon enough to see whether I like it or not.
The video details some other things you might want to know prior to the game's release. So click play and tell me what you think. I'll be watching the comments.