Microth published a new input concept for mobile devices on their site dubbed KeyWheel.

The KeyWheel differs from the Apple iPod TouchWheel in that it is using absolute and discrete positioning. The KeyWheel takes into account the starting position of the gesture and it's length.
The KeyWheel advantages are that only a small number of keys is necessary for it to work and all selections are made by the same movements, which should make it easy to use. It works a bit like the old dial on phones actually. I do not know if the KeyWheel is break-through user interface idea or not. Microth also offers input software for mobile devices called inPad. I guess they are looking for hardware manufacturers to give the KeyWheel a try.
More details on the Microoth site.

Circular key placements are hip, just look at the new B&O Serene Mobile Phone.