I've got a Hitachi P42H401 42" Plasma TV as my main (and only!) TV. It's kind of an oddball TV in terms of its specifications - it's actually a 1080i native set. Hitachi tends to advertise it as simply 'HD1080'. It's not a 720p set, but it's also not a full 1080p (1920x1080 pixels). It's 1024x1080 'native' resolution, as far as I know. It's not the latest and greatest tech but it is still very, very sharp and in all honesty, at the proper viewing distance for a 42" set, 1080p is really overkill and drives the cost up considerably. I actually prefer the 1080i resolution to 720p since most of what I watch is broadcast, and 1080i is the more common standard - 1080i broadcasts, like Monday Night Football or Sunday Night Primetime TV look absolutely phenomenal.
The TV does, however, accept a wide range of signals. It converts everything to 1080i before it is actually displayed, but it will take basically any signal you can throw at it - 480i (SDTV), 480p (DVDs, Nintendo Wii), 720p (Fox broadcasts), 1080i (most other broadcasts, Gran Turismo 4 on Playstation 2), and even 1080p (upconverted DVD, laptop via DVI->HDMI at 1920x1080). The scaling is actually very good - 480p looks perfect, as do most 720p sources. Interestingly, when running a computer as a source (DVI to HDMI adapter) the picture looks better with the output resolution set to ~1360x768 or so. I don't recall the exact resolution, but at 1080p a computer desktop does 'jump around' a bit vertically. It's not noticable at viewing distance but the picture just looks a bit better by turning the resolution down a bit. It works great for playing back h264-encoded 720p video files.
The only ways in which I give this TV any marks down are the menu interface, the remote control, and the stand. The menu interface is actually well thought out, and getting to where you need to go is straightforward - it just takes a while to respond and is not nearly as snappy as it should be. Also, after switching inputs, you need to hit 'exit' to clear the menu of inputs from the screen, otherwise it stays up for about ten seconds. On the topic of inputs, the TV does let you choose from a list of predetermined device lables like DVD or Cable, as well as the standard names like Input 2 or HDMI Front, but it doesn't let you spell out a custom one like Wii, Computer, or PS2. The remote is nice but despite being 'universal' it lacks codes to control my LG DVD player. The stand is relatively sturdy, but it does allow an almost disconcerting amount of forward-backward movement of the TV on the stand. It feels wobbly while you set it all up but once it's done the TV is actually stable.
All in all - a great purchase when you can get it at $1000 or less.