NV News posted some information about NVIDIA's upcoming ForceWare 80 drivers. A beta version of these drivers recently leaked and here's the changelog. One of the biggest improvements is mix and match SLI which will enable you to pair two NVIDIA cards from different vendors.
TV-out / HDTV-out support for even higher resolution gaming support
Mix and match vendors - for example, pairing an SLI supported graphics card from MSI with one from BFG or XFX
Mix and match framebuffers (via Coolbits) - pairing a 128MB graphics card with a 256MB graphics card
Ability to enable vsync for all Direct3D and OpenGL games
Dynamically enable/disable SLI - rebooting is eliminated!
Primary Display Switching
Auto Display Detection
Additionally, the number of games optimized for SLI has now been increased to 150.