At this point I'm reasonably sure it's going to take the form of a tablet.  But we still don't know what their target use cases will be...  I'll throw one out that I haven't yet seen:<p>The tablet will be the perfect remote for apple tv.  Infact, apple tv could become moot as people simply plug a regular PC to their TV (which has now become a glorified monitor).  With the ability to move a pointer and type freely, the notion of a set top box is now a thing of the past.  You're free to surf the web, watch online tv, use iTunes, use bittorrent, etc... anything you can do on a PC is now available in the living room.  What we currently call the desktop/PC is now the main form of video consumption.  (I'm looking a few years down the road of course, these changes won't be instant).