And here's another motherboard from Asus with watercooling support. German hardware site PC Games Hardware spotted the Asus Maximus 2 Extreme motherboard today at CeBIT. This motherboard is based on the Intel P45 chipset and features the ICH10R southbrdige.
The motherboard supports CrossFire, dual DDR3 1600MHz memory and 1600MHz FSB. Asus has developed new CPU Level-Up technology which should make overclocking easier and there's also a EPU chip to improve the power efficiency of the motherboard.
The site also writes they've spotted a P45 Platinum motherboard from Asus with DDR2 memory support.