Of the options you mentioned, I should point out that only the Sanyo and Mitsubishi are actually available for less than your $2,600 maximum. If you really are putting them all into contention, I feel the Panasonic and Optoma are worth the premium.
The 1080UB is supposedly quite impressive in terms of black level, and should have a noticeable advantage over these other units, but I don't think that you would find that aspect of image quality lacking in the Panasonic or Optoma, and the new Epson is more expensive than either of these offerings.
At your screen size, the Sanyo would be a good choice, though you shouldn't expect to keep the lights on... ever. The Mitsubishi is the obvious "bang for the buck" candidate, but if you really do have the budget for the more expensive projectors and wouldn't find a few hundred dollars a serious financial impediment, it's worth the difference. If your budget is <$2,000 and you have a Blu-Ray or HD-DVD player, or both, the HC4900 is a killer deal, but it gives up some black level performance.
HDMI 1.3 isn't a make-or-break feature for displays, and I'm not going to take the time right now to dig into it, but I don't know that any of these projectors are capable of the expanded color-space technologies, which, though there is no actual source material at the moment, would be the only benefit I can see over HDMI 1.1 or 1.2.
24Hz(x) playback is nice, but it, too, isn't make-or-break. I think I would probably make my choice first and then revel in the bonus features, rather than make these marketing-driven additions a major selection criteria. If you've never seen 1080p/24fps, it would be difficult for you to imagine exactly what the improvement is because "judder" is something we've all lived with in our displays for decades, and, for the most part, have never really complained about until the possibility of overcoming it became a reality.
To summarize, I think if your budget will allow it, the PT-AE2000U or the HD80 are your best choices. They're not the most expensive option you listed, but also not the least expensive. They are, however, worth the price premium over their lesser brethren. The Epson 1080UB, though I can't make a first-hand assessment, probably isn't worth the same difference in price, but it almost certainly will be an improvement. My main concern with it is that Sony has just released the VPL-VW40, an LCoS projector, at the same price point, and I would be shocked if the on-screen image, calibrated with movie-viewing in mind, didn't give the LCD-based Epson a real run for its money. In the interest of full disclosure, it should be mentioned that the 1080UB is available with a $200 rebate at the moment, so at this temporary price point it is a very worthy consideration over all of this competition. I'm not dwelling on that point, though, because it is only good until 1/31/08. If you can pull the trigger now, it might be worth picking up at that price and at least trying it out for an hour or two in your theater. Otherwise, if its price returns to the $2,999 MSRP, my recommendations stand.
I really would like to see the new Sony. Somewhere in this forum, a poster said they'd been told by a Sony representative that is a renamed VPL-VW50, meant to march on as the budget alternative to their new VW60. I've seen the VW50 many many times and absolutely love it. Art at ProjectorReviews.com even called the VPL-VW50 "a very good value (price/performance)" at an MSRP of $4,995. Knock $2,000 off that for the VW40, and, although nearly a year has passed, I think we're looking at a knock-out deal. Maybe you should take the time between now and the actual ship-date of the Sony to save a few hundred bucks and put that into serious contention.
