The magic mouse has the ability to do momentum scrolling when you swipe. This is the type of scrolling that you have on the iPhone, where the swipe scrolls and then slowly comes to a stop. But momentum scrolling is only available as a magic mouse option when you are using Snow Leopard (OSX 10.6), not Leopard (OSX 10.5).

But fear not, if you are using a magic mouse with Leopard, you can get the momentum scrolling enabled, you just have to do a little bit of work:

1) Open a terminal application window, the terminal is found in Applications > Utilities.

2) In the terminal window, enter this command and then hit the Enter key: defaults write com.apple.driver.AppleBluetoothMultitouch.mouse MouseMomentumScroll -bool yes

3) Close the terminal window/application.

4) Open System Preferences and select the Mouse preferences.

5) Uncheck the Scroll option, then check it again.

Once you do that, you should have momentum scrolling enabled on your magic mouse.