Vitra is the source for this one. Oh sure, everybody makes mobile tables, but in my mind Vitra was the first one to put it together with a concept for a more flexible way to work in the Mono Wall, what I call the original the vertical desk.
Sadly Vitra has really curtailed the breadth of the Ad Hoc components sold here. There used to be a whole system of two part tops whereby you would combine two different shapes on each half of the desk to create some unusual and useful shapes. I have one in my office and its my favorite shape. A rectangular desk on one end, and a rounded cantilever on the other that allows your work to wrap around you a bit. But we still have the mainstays available - rectangles, and rectangles with an angled face, and I believe the graceful ovals are still available. These basic shapes are the ones that really work best with the vertical desk.
I believe that castors are an option on all tables. And the Ad Hoc system has a big range of accessories as well.