Keys now are pretty big (about 2x2 cm), so we have to position them very close to each other. Since pressing four keys instead of one is not good, we've raised surface on every key to have usual 4 mm distance between keys' tops. Surfaces have to be flat because no one wants optical distortions.
In the process of moving, adding, removing, and reshuffling keys around Optimus eventually got a new name (it's not 103 anymore). Details will be revealed on the first day of CeBIT :-)