According to Digitimes, AMD is on track to release the new IGPs in the integrated Radeon line next month. The RS780 series chipset, along with its entry-level cousin, the RS740, are both slated for a release in January. Following that, the R780D and R780C are expected later in the year.
The primary advantage of the RS780D is multi-GPU support, whereas the entire RS780 line brings things like DX10, UVD, HDCP and DisplayPort support. They will also be some of the first AMD chipsets in action that will support coupling discrete graphics with integrated graphics, which can be a boon to people who buy small but then upgrade later.
That same type of technology has seen limited use in mobiles in the past, where both discrete and integrated graphics could be toggled, though they could not be used at the same time. It would a benefit, it seems, to have a system that could power off a power-hungry video card when it is not required and instead rely on an integrated unit.