Well I don't have a HDTV and don't plan on getting one.
I recently bought a HD compatible projector, and run my 360 through VGA cables (so no HDTV, but max 360 resolution). I also have a MONSTER optical digital cable for my surround sound so its pretty sweet.
I was weighing up the pro's and con's with the HDTV, but I figured, for the money, I would prefer a screen twice the size, for half the price. Its LCD anyway, so its all good.
I'm sure a HDTV will be the way to go in the future when the price comes down, but for just now, I don't think a good projector can be beaten on the basis of price / screen size....