http://support.apple.com/kb/ht4254

Inertial Scrolling and Three-Finger Drag Gesture Support

These Mac portables support inertial scrolling and the three-finger drag gesture after you install Magic Trackpad and Multi-Touch Trackpad Update 1.0:

MacBook
MacBook (13-inch, Early 2009)
MacBook (13-inch, Mid 2009)
MacBook (13-inch, Late 2009)
MacBook (13-inch, Aluminum, Late 2008)

MacBook Pro
MacBook Pro (17-inch, Mid 2010)
MacBook Pro (15-inch, Mid 2010)
MacBook Pro (17-inch, Mid 2009)
MacBook Pro (15-inch, 2.53 GHz, Mid 2009)
MacBook Pro (15-inch, Mid 2009)
MacBook Pro (13-inch, Mid 2009)
MacBook Pro (17-inch, Early 2009)
MacBook Pro (17-inch, Late 2008)

The following Mac portables support inertial scrolling after installing Magic Trackpad and Multi-Touch Trackpad Update 1.0:

MacBook Air
MacBook Air
MacBook Air (Mid 2009)

MacBook Pro
MacBook Pro (15-inch, Early 2008)
MacBook Pro (17-inch, Early 2008)