To nobody's surprise, iFixit has managed to get hold of an iPhone 4. And guess what they took it back to the lab, and did an iPhone 4 teardown. This is what they got from it:
"We have confirmed that the iPhone’s A4 processor has 512 MB RAM, unlike the iPad’s more limited 256 MB. This decision may have been made fairly late in Apple’s development cycle, because early leaked prototype phones only had 256 MB."
They have also confirmed that the retina display is protected by Gorrila Glass
"The front glass panel of the iPhone is constructed of Corning Gorilla Glass, a chemically strengthened alkali-aluminosilicate thin sheet glass that is reported to be 20 times stiffer and 30 times harder than plastic.
Gorilla Glass holds many advantages as the iPhone 4’s front panel including its high resistance to wear and increased strength from a strengthening process."