If you want to be able to get older Mac laptops to have scroll functionality and a few other nice features included in newer models try this http://www-users.kawo2.rwth-aachen.de/~razzfazz/iscroll2/.

I have to admit I haven’t yeet used it as I normally use a USB mini mouse with scroll wheel that works just fine. But it look like it could be useful, especially when it becomes more thoroughly tested on tiger.