In addition to iPhone 4 preorders starting Tuesday morning, Apple also rolled out a relatively major update to the Mac mini. The little headless Mac now comes in a unibody aluminum enclosure like its notebook brethren, and sports a new HDMI port, SD card slot, and improved graphics performance.

With the new casing, the mini is 7.7 inch square and only 1.4 inches thick, including an integrated power supply. This is down from 6.5 inches square and two inches high in the previous model—it appears Apple is trying to get the mini to look a lot like the Apple TV, which is also a 7.7 inch square with an HDMI port.

Both flavors of Mac mini now come with the NVIDIA GeForce 320M, which is the same integrated GPU that comes in the current MacBook (the last mini came with a NVIDIA GeForce 9400M). This, according to Apple, will bring "twice the graphics performance" of the previous Mac mini model. The machines come in either 2.4 or 2.66GHz flavors with 2 and 4GB of RAM as a base respectively, though they can go up to 8GB of RAM with build-to-order options.

Like before, the high-end mini is actually a compact Snow Leopard server, with two 500GB hard drives and no optical drive. That model goes for $999, while the entry-level model starts at $699—a surprising price increase given the relatively minor changes in internal hardware. Additionally, Apple has finally given users an easy way to upgrade the Mac mini's RAM themselves with a circular panel on the bottom for easy access.