OLED screens are great. I have been waiting for the mainstream use of them in larger format displays (not just small devices). I know they've come a long way in the blue material that was really lagging behind in the brightness half-life. Still great to see them just starting to get into the mainstream (Droid Incredible and Nexus as well!)
Universal Display Corporation has made some great strides in the flexible OLED tech as well that looks really promising. I know the govt is also giving them research money for their developments. They have some really cool videos on youtube that showcase their R&D tech.
I had a old creative mp3 player (Zen microphoto) with OLED and it looked great. The picture was nothing to write home about(small screen), but the viewing angles where simply the best I have ever seen.
IPS LCD should be more then enough for iPad anyway(viewing angle wise). Guess they will have to ramp the production. OLED will take some time to be in the right price range.
The good thing about OLED is that it's borderless. Instead of trying to make a single 1024 X 768 screen, they could just piece together multiple screens. Mitsubishi did it and made a 155 inch screen (http/gizmodo.com/5377145/mitsubishis-modular-155+inch-oled-screen). That would be way more cost effective!