It's a 27" LED-backlit IPS display, 2560x1440. This is pretty much the same display panel you will find in other 27" IPS displays, such as the Dell Ultrasharp.
The 2012 model is different in that the display panel is optically laminated to the glass. This is supposed to result in reduced glare over previous models.
If you're interested in more detailed measurements, keep an eye out for Anandtech's review once the 2012 model ships.