well, I don't think webOS can tell if it's DC or AC powering the touchstone (TS). What you could do is play with the orientation of the Pre when you place it on the TS, and have MS respond accordingly. e.g. If I put my Pre landscape left before I place it on TS, it will change mode to clock. but if I place it landscape right, it will change mode to mp3. If I place it portrait up, then it behaves as default.