1024x1024 is the highest I've seen on any plasma thus far, however Hitachi and Panasonic are going to introduce some high end models next year thay may be even higher. The only flat panel displays with higher native resolution would be found on computer based monitors that are designed more for gaming and graphics design/art rather than being used as a TV. Besides, most HD channels are still in 720P which is a lower native resolution.
...Any on the horizon?
My Sony KDE-42XS955 which runs at 1024x1024 has an amazing picture. I can't even imagine what 1920x1080 looks like.
Will there be any programs filmed and broadcast at that resolution?