MagicPrefs is a free utility that runs from your menu bar and fixes the problems some Mac Pros had with the Magic Mouse.
This app goes way beyond fixing the tracking speed. This little utility allows you to assign actions to two, three and 4 finger clicks. Also to one, two, three and four finger taps. You can define two and three finger swipes for left, right, up and down. You can even define drag and pinch movements on the surface of the mouse. Pre-defined actions include control of Spaces, Dashboard, Expose, Quicklook and many others. You can create, load and save presets as well. Some of the gestures are a bit difficult and take some practice, and the app warns you which ones might be tricky.
There is even a real time display on the app that lets you test different combinations of motions to see how they will work. For people who have a Magic Mouse that works great, you will love the power of this app. If yours was a dog with your Apple hardware, this app may fix all that.
The developer says the app will eventually wind up as a preference pane, and that it will always remain free.
The app requires OS X 10.5 or above. The price is very, very right, and the app fixes a lot of the weaknesses in the Magic Mouse. I say, go for it, and let us know in comments how it works for you.