iMac - Faster processors (all based on Intel Core architecture) upgraded RAM (1333MHz DDR3), improved graphics (now all are dedicated, with up to 1GB of VRAM), option of SSD on 27".
Mac Pro - New 4, 6, 8, or 12 core processor options, 1333MHz RAM in 6core and 12core models. new 512GB SSD option.
27" LED Cinema Display - 2560-by-1440 resolution. With 60 percent more pixels than the 24-inch LED Cinema Display. Built in iSight camera and mic. 49 watt stereo system with subwoofer.
Magic Trackpad - 80% larger then a MacBook Pro trackpad, Bluetooth, Same height and angle as Apples wireless bluetooth keyboard, Batteries have a life of "up to 10 years"