This is some of the most interesting speculation I've come across--and it doesn't seem too far out into conspiracy world. (h.t. Atrios).
The Saudis are concerned about the rise of Iran. (This piece doesn't say so, but Bush's invasion of Iraq contributed greatly to the rise of Iran). The instability in Arab lands, especially if it creates new havens for terrorists, concerns the Saudis as well. They may need to ally themselves with Pakistan--but again, they would seek a terrorist-free Pakistan, as opposed to, er, present-day Pakistan.
So: maybe somebody in Asia decided to give up bin Laden, and that's how he fell into U.S. laps?
One wrinkle in the official U.S. story interests me. There were supposedly no electronic connections at all to bin Laden's hideout--no internet or cell phones. This suggests they are convinced that U.S. technology can trace any electronic link. Yet, in the end, the very electronic silence of this large comfortable house was one thing that attracted attention. So: the U.S. can track your internet use, listen in on conversations, follow key words, etc., and they may also notice if you're not in the ether at all.