Recent article on an AppleTV hardware set up to project newer iPads (iPad 2 and newer) in the classroom. The ability to roam with your tablet moves the interactive surface from the front of the room (like a Smartboard) to anywhere in the room.
Details a couple of different ways to use a first-generation system (SmartBoard) with next generation mobile tablet devices. These are two interesting ways of bridging the gap between the two types of systems, if for instance, your institution has already invested in SmartBoards, but you also have access to a tablet device. Includes links to software.