Some people like mice. Other people like trackpads. Apple likes both as long as they come with their credit cards.
The updated iMacs offer both as options for no additional cost. During the build process, buyers are presented with the option of either the the Magic Mouse, Magic Trackpad, or, for an extra $69, they could get both. The standard Apple Mouse is also available for those not digging the whole multitouch control scheme, which just so happens to be one of the best things about OS X.
