Is information about what fell into a black hole stored on its event horizon?

It seems that that is indeed the case if you can trust the mathematics!

Recent calculations by the folks who study quantum gravity theory and superstrings have confirmed what Stephen Hawking and his collaborators proposed a decade or more ago. Evidently, the information contained in matter that falls into a black hole is by some curious means encoded in the pattern of frozen quantum fields at the horizon. This raises some interesting possibilities that we could resurrect clocks, humans, spacecraft, whole planets, into something like their pristine form if we could magically reverse the infall and collapse process.

This result is only a few years old, and many physicists who study quantum gravity theory believe that this mathematical result means that we have reached a watershed moment in history in understanding the connection between quantum mechanics and gravitation theory. Quantum mechanics deals with statements about the information that we can extract about a quantum mechanical process involving observation. Now this same information language can be applied to configurations of the gravitational field and space-time itself.