There are three new mobos on display, the 9X, 9P, and 9G. Presumably, the 9X is based on the Intel 925X chipset, the high-end replacement for the 875P. The 9P, then, would be based on the 915P, the 865PE replacement, and the 9G would ue the 915G chipset, which is a 915P with built-in Extreme Graphics 3.
The 9X packs a load of new features, including an ICH6R south bridge for I/O, Socket 755 for "Prescott and Tejas" processors, and support for dual channels of 533MHz DDR2 memory on an 800MHz front-side bus. There's a single PCI Express X16 slot for graphics, plus a pair of PCI Express X1 slots for other expansion cards and three PCI slots for slow and old stuff. The board has four Serial ATA ports and one ATA/100 port, all provided by the ICH6R south bridge, complete with RAID flavors 0 and 1. A VIA RAID chip adds two more ATA/133 ports with additional RAID support. Also, this puppy conforms to Intel's High-Definition Audio standard, no doubt with audio driven by the ICH6R chip, with 7.1 outputs and a Universal Audio Jack (UAJ). MSI has included support for eight USB 2.0 ports, and I'd guess the ICH6R drives them all. Gigabit Ethernet, probably using a PCI Express device, is optional.
The 9P differs from the 9X only slightly. Somewhat surprisingly, the 9P supports DDR2 533 memory, though without ECC support. The 9P only optionally includes the R variant of the ICH6, so penny pinchers can do without RAID if they wish. Beyond that, the 9P's layout looks virtually identical to the 9X, if MSI's web types have gotten their pictures right.
The 9G is a different animal, also with DDR2 533 support, but definitely without the RAID version of ICH6. Intel's Extreme Graphics 3 affords the 9G dual independent display capabilities. MSI calls the 9G the "Latest Corporate Stable Platform." Sleeping pills not needed.
The big news here is the move to DDR2 533 memory across the board for Pentium 4 systems. We'd generally expected a move to DDR2 on the high end and a slower migration for mainstream products.
On the server side, MSI has announced the K8D Master 3, a dual Opteron board with 12 DIMM slots supporting up to 24GB of RAM. 64-bit operating systems only need apply, thanks.