Just a heads up, I've been using this:
http://www.getidisplay.com/
It lets your iPad function as a second monitor for your PC or Mac, I shift interface windows over to it to keep the main display uncluttered, or have my camera controls on it when running the rest of the astro software on the main computer screen. It is quite handy. The graphics aren't speedy but it works great for having a second app open.
It is kind of cool to move something across from your desktop and walk off with it to show other people, and the touch surface works as you would expect most of the time. The screen update is slow, only a couple of times a second, but it is still very cool and useful.
