A few roadmap slides show that AMD's SB850 chipset--along with the RD890--will be available in Q4 2009.
It's unknown whether or not the images are leaked, officially released, or completely fake, however Expreview posted three AMD slides highlighting the company's chipset roadmap. The slides are comprised of the south bridges, performance north bridges (IGP and discrete), and mainstream / value IGP north bridges. As it stands, the SB850 chipset will be available in Q4 2009 as well as the RD890 and the RS880D chipsets. AMD's slides also reveal that the 785G chipset will actually be released in Q3 2009, however no specific dates were set.
According to the images, the SB850 will be the last south bridge chipset using the new SATA 3 controller with speeds of 6 GB/s this year. Reports speculate that the chipset will only support AM3, and offer Gigabit MAC, AHCI 1.2, 6 SATA 3 interfaces, 14 USB ports, and RAID 5 and possibly the second generation PCIe 4X.
The RD890 north bridge chipset, on the other hand, offered no details in the provided chart, however it may support HT 3.0, 2x16 PCIe, and enhanced Quad Crossfire X 4x8 support. As for the RS7880D, this chipset will include the RV620 GPU (Radeon HD 3400) with a core clock of 700 MHz, and also offer support for DirectX 10.1, UVD 2.0, and CrossFire 2x8.
Finally, the AMD 785G IGP chipset will be the last of the "700" series to launch this year and was designed by ATI for Phenom processors. The AMD 785G shares similar traits to the AMD 780G released in Q2: both chipsets offer PCIe 2.0, HDMI, and possibly the Radeon HD 3200 (clocking at 500 MHz). However, the 785G will support DirectX 10.1 and UVD 2.0.