Slightly higher clock speeds (2.2gHz & 2.4gHz vs. 2.16gHz & 2.33gHz) on the Santa Rosa chipset, larger bus (800mHz vs. 667mHz), 4GB memory capacity (was 3GB), and nVidia 8600m GT graphics. The 15" model gets a LED-backlight display, while the 17" model gets a $100 built-to-order 1900x1200 option (17" is still florescent backlight).
http://www.apple.com/macbookpro/
http://www.apple.com/macbookpro/