I have a Panny AE900U with one HDMI input. Gefen, and others, make an HDMI video switcher, taking for example 4 HDMI inputs to the switcher and one HDMI output going to the Panny's HDMI input.

The current Gefen model is EXT-HDMI-441, but the specs say HDMI 1.2. The question is what does the upcoming HDMI 1.3 do that I need? Should I wait for the version with 1.3?

The audio from the DVD player, cable box, etc goes to the receiver.
Take Aim

I think HDMI 1.3 is going to mostly deal with audio, not video, so unless your planning on using the 3w speaker built into the projector... :)