FUD Zilla unearthed some information about the upcoming AMD SB850 southbridge, which is scheduled to arrive in Q4 2009 with the RD890 northbridge. The site says the new southbridge will consume 4W, which is 0.5W less than its SB750 predecessor.
The new Southbridge brings A-link with X4 Gen 2, PCIe 4x1 Gen 2 as well as 14+2 USB 2.0 ports. The previous SB750 only had 12+2, which should be enough, but hey more is usually better. SATA gets upgraded to 6x 6Gb/s which is another name for SATA 3.0 and of course RAID 0,1,5 and 10 support is here. It also has integrated clock generation and Gigabit MAC.