An alleged iPad 3 display component ends up in hands of MacRumors.
The iPad 3 that Apple will unveil on March 7 is going to feature a so called Retina Display. This is pretty sure now. MacRumors now even got their hands on the iPad 3 screen component and confirmed under the microscope double resolution of the iPad 3. The iPad 3 will have 2048x1536 pixels compared to the 1024x768px today's iPad is offering.
Apple is likely center the iPad 3 marketing around the new screen. Every other expected upgrade is not ground breaking. There will be better cameras and a faster CPU in the iPad 3, but these improvements would not make consumers upgrade from the iPad 2 to the iPad 3. A retina display is though a big argument as display of content will be dramatically more beautiful.