The RackMac mini Xserver supports one half-length, x16 (x4 mode), PCIe 2.0 card to enable the use of professional video capture cards, 8Gb Fibre Channel cards, 10-Gigabit Ethernet cards, and RAID controller cards with a racked Mac mini all in 1U rack space.
ENGADGET: Sonnet announces RackMac mini Xserver, makes Apple desktop IT life seem more legit