With the release of the CAnon 5DMrkII (and to some extend the Nikon D90), a whole new industry is taking shape: low budget film making. As with the coming of any new market, a supporting industry has to take shape. A few suppliers have already stepped in and my favorite so far has to be Zacuto. They have released a video showcasing their product on Vimeo.
While the price of these accessories might seem high, actually they are in comparison to the price of the camera, you have to see them as long term investment. What ever you upgrade to in the future, they will always work.
I am sure we will see some China manufacturers sell knockoff of these soon, if you are willing to run the risk of the mount falling apart during shooting.
Most useful item of the kits: the follow focus! I am working right now on a ghetto version of it involving rubber bands and wood sticks, I am not kidding.