Now that the availability in stores is imminent a couple of reviews pop up. As far as performance is concerned the boards sit tightly together. Users have to decide which brand to choose and it will probably all come down to the different feature sets the mobos provide, e.g. if they offer RAID or not. Shuttle AK31 v3.1 Review @ Techhard
Review @ LegionHardware
MSI KT266Pro-RU Review @ OCWorkbench
Review @ AMD3D
Review @ BlargOC
EPoX 8KHA+ Review @ Overclockers UK
Review @ Planet3DNow (german)
Side note: ABIT KR7A-RAID expected within a week according to TheInquirer.