Things definitely don't work the way they should, but I bet it'll get fixed. Open the following link on the iPad2 and iPad3, while holding the device in the horizontal orientation, so the image is as big as possible.
http://img29.imageshack.us/img29/1769/retinatest.jpg
Both the old and the new iPad resizes the image to 912x684, even though the source image is 3648x2736. This size makes sense for the old iPad, but it makes no sense on the new one. Because of the resizing, they will look almost the same. The expiration on the license plate is not readable on either device.
Now, hold your finger on the image and tap "Save Image". It will save the full sized image to the "Photos" application. Open it up on both devices and don't pinch zoom. On the retina display, I can read "2012 Ford" under the expiration date. On the old iPad, it's just a gray smudge.
So it depends on how you are viewing you images. They might look the same or the retina might look quite a bit better. Safari in my opinion is broken because it doesn't resize images correctly for the retina screen.