An educated guess is that Optimus Technology is a tool for connecting a discrete NVIDIA GPU with Intel’s new GPU-endowed processors. The technology will work with both Arrandale and Pine Trail, which surely indicates that it works in some way to balance the workload depending on use. An extension of the Hybrid Technology more or less, a technology we heard rumors of long ago.
Its purpose is to optimize the mobile experience by letting the user get the performance of discrete graphics from a notebook while still delivering great battery life.
How it works and how effective it really is remains to be seen, but it sure sounds promising.