Since we only had a raw iPad 3 display with no method to power it, taking high quality photos of the pixels was difficult. Still, even with the relatively poor lighting, you can easily make out the pixels on each display (made up of red, green and blue elements). We highlighted a cluster of 4 pixels (2x2) from the iPad 2 to compare it to the same area on the iPad 3. On the iPad 3, the same cluster was occupied by 16 pixels (4x4) -- exactly twice the resolution in each direction.
Extrapolating out, the iPad 3 screen should carry a full resolution of 2048x1536, exactly twice the linear resolution of the iPad 1 and iPad 2 which is 1024x768. Such a screen should be able to display much sharper images as compared to the previous generation iPads.
Confirming widespread rumors, MacRumors has gotten hold of an iPad 3 display and physically counted the pixels.
An exciting confirmation, indeed.