I would go ahead and get the 5DII as well, I honestly think the 5DIII is going to be a more stills oriented camera. I'm not saying the video won't have improvements, but it will remain a still camera at its core. Canon has said countless times that they never anticipated DSLRs taking off in the video world the way they did. I'm sure the Cinema DSLR will be better suited for your needs than a 5DIII, but I have a feeling it won't be out until much later in 2012 and who knows how much it will be. Some have suggested it will be more than the C300, but I seriously doubt that.
And don't worry about getting stuck with the 5DII, it's an awesome camera and there will be thousands of T2i/60D users clamoring to get a full frame body, so I doubt you'll have any trouble selling it even after the new ones come out.
Just remember people are still using the original 5D, and the 5DII will continue to be a good camera for years to come. Go ahead and get it now, the longer you wait the less experience you'll have.