It's called Terminal Server, and it has been around and in use for DECADES. Without a stupid iPad. Heck, EVERY Windows Mobile phone had a client for this built-in from the start.
Just because Apple now finally also caught on to the Tablet PC concept that Bill Gates was so excited about YEARS AGO doesn't make the iPad a revolution. This concept has been around long before His Steveness - the man who always said that he even couldn't imagine a customer for a notebook computer except for maybe a journalist - pretended to re-invent the wheel. Again.
Just because people see new opportunities over and above the devices original concept, doesn't mean it's copying anything. I've seen and heard lots of vapourware from Microsoft, I've yet to see to come to market (the amazing physical games interface, the multi touch mouse?). Did you mention windows mobile and windows mobile devices? How are those doing these days?
This isn't a tablet PC, you've missed the point. Never mind. It's a media consumption device, with specialised OS to focus on just this, it's not a fully functioning portably computer.