[w0utert]

I'm not really sure if it's a glitch in the tool or that the resolution is (deliberately?) misreported by my browser, but on my iPad 3 it reports 1024x768.

A nice extension to this would be to add some kind of database of popular mobile devices, so you can detect the device type from the reported attributes. I think you coud extract some interesting device usage statistics out of it.

[NLips]

That's the size reported by Safari so that pages scale correctly for a "retina" screen.