None of the HTC WM6 devices except the HTC Advantage have a VGA output, so this is the only device we know of that would work with a projector.
As I understand it, all the projectors that are WIFI enabled for use in classrooms and the like that receive their image wirelessly require software to be installed on the Windows XP/Vista or Apple Mac laptop or desktop PC being used with them. We are not aware of any projector that comes with or has the software for Windows Mobile 5 or 6 to download that would enable a PDA device to be used with it.
That's a pity as it would be a great thing to do.