I hate to say it being an iPhone user, but it essentially performs an identical role to the iPhone on a slightly larger scale with a pen. To me being a programmer and knowing those inside Microsoft it seems just their way of keeping up with apple yet again, the Zune and a phone at one point being other examples.
Perhaps they may win this one due to the iPad but it does seem to be very popular but this does seem more practical, whether apple will re-task and let Microsoft pull ahead on this one is the important question. Mainly as we are all aware of the strict legal situation they are in and it may extend onto the portable medium if they being to squeeze apples market share that said apple wont rollover on this one.
That said apple do have the fact many associate now more so the portable stylish devices with their brand due to their exposure more so than the "big ole Microsoft" as many still aren't white washed by windows 7 and the latest IE that they are continuing to push heavily at the moment.