Just another quick follow-up... I compared a color bar test pattern on my iPad 2 and 3 and a new Panasonic Viera plasma TV using the hdmi adapter. I asked my gf to look at each color bar on the tv and pick which iPad was the closest match. One color bar was a toss up, all the others were best matched by the iPad 3. The Panasonic is set to a good setting (I researched on avs forum and cnet).
So, my iPad 3 has now been the best match vs. the 2 for two decently calibrated hdtv's. The whites are clean and bright whites. The difference with the iPad 2 is mostly noticeable with some blue hues where the 2's are a lighter baby blue and the 3's are a deeper indigo and sometimes even towards purplish... yet these blues (unexpectedly for me) are close to those displayed on a Sony LCD and now a Panasonic plasma HDTV.
I'm really happy with this turn of events. When I get a chance, I'd still like to compare with store models. My guess is that the displays will be very close... I'm not a panel expert, but I'd think uniformity based on the same parts and process is most likely.
My iPad is a 64gb 4g+wifi AT&T week 9.