Most imminent on the horizon right now is ForceWare release 75, which will bring a number of improvements for SLI performance and 64-bit Windows, among other things, but release 75 will not be multithreaded. The next major iteration of the driver, release 80, is slated to bring support for multiple threads. We may not see this version for a few months; NVIDIA hasn't given an exact timetable for the completion of release 80.More info at The Tech Report
NVIDIA's ForceWare to go multithreaded

NVIDIA said it will soon start developing multi-threaded ForeWare drivers. Ben de Waal, NVIDIA's Vice President of GPU software, believes multithreading in video drivers might improve performance with five to thirty percent.