According to Ben's Git commit this less than 100 line patch should provide Zaphod mode capabilities for at least simple configurations. Zaphod mode is an older, alternate way for configuring dual-head mode support under Linux (rather than just configuring the displays with RandR) and is supported by some drivers. Setting up Nouveau's Zaphod mode requires using the ZaphodHeads option (similar to the other supportive drivers) within the xorg.conf for specifying the RandR outputs that should be used for a particular driver instance.
Also being worked on recently is Nouveau power management, especially after they received a load of NVIDIA video BIOS dumps to help with timing management. For those interested in OpenGL performance with this open-source NVIDIA driver written by the community, earlier this month are our most recent Mesa 7.9 Nouveau benchmarks compared to NVIDIA's high-performance proprietary driver.