Is it only the camera rotation or is Apple switching from BGR to RGB?
But it's kind of funny, anyway, since the home button is at the bottom of the screen, so the sub-pixels are arranged top-to-bottom when you hold the iPad with the home button where it should be.
It does create another strange effect, though. Since the screen effectively redraws sideways if you hold the iPad in portrait, scrolling vertically quickly makes stuff look a tiny bit distorted; horizontal lines look a bit slanted (like taking a picture out of a car using a cellphone camera, but much less so).
[1] I can only assume the new iPad's LCD is more inert in some way? Smaller pixels, slower crystal?
On the iPad, on the other hand, there are tons of horizontal lines in a table view, for example.
Also, I thought about the 60 Hz thing, and I think high frame rate is a bit of a red herring. After all, the lines actually are slanted; the higher the frame rate, the fewer degrees they're slanted at the same scroll speed, but whether we notice the slanting is independent of the frame rate.