The Lemur and Dexter are each about US$3K, which might seem like a lot, but consider this. The "good" control surfaces for Color cost over US$15K, with the cheap alternative running about $US8K. These are big, single-purpose devices, whereas a multitouch display can be your color control surface today and an audio mixing board tomorrow.
Still, in a world where color correction software that once cost US$25K is now a free toy surprise inside a box of crackerjacks, the solution should be clear: clever software that takes advantage of UI devices that are inexpensive because they're not purpose-built for our niche. In other words, by the time a multitouch accessory becomes so inexpensive that you can't afford not to have it, it may well be a default shipping option on an iMac.
Either way, I hope Apple's Color team, as well as developers at Iridas, Assimilate, Adobe and Autodesk are looking at these new interfaces and thinking of ways to let us cut, color and combine our movies with them.