I still stand by my previous statement of the Sharp Aquos line of TVs; they have the least input lag of any manufacturer out there, and a few of their models actually have a video processing mode specifically designed to address input lag for gaming and reduce it even further;
I just ordered a 1080p 32" model for my dorm at college (mainly because my 42" at home is too big for the dorm room lol), and it has their Vyper Drive game mode; the model is "lc32e67u" and I paid $600 at http://www.6ave.com They're doing some site and database restructuring, so I have to wait a little while for it to arrive, but it's worth the wait.

