UPDATE: Other interesting stuff added from National Journal:
How did the helos elude the Pakistani air defense network? Did they spoof transponder codes? Were they painted and tricked out with Pakistan Air Force equipment? If so — and we may never know — two other JSOC units, the Technical Application Programs Office and the Aviation Technology Evaluation Group, were responsible.
Yeah, there’s that. Or maybe the Pakistani aid defenders fell asleep, were bribed, drugged, or taken out, out on smoke break, lost comm., had an equipment failure, were overtly or covertly tasked to support the U.S. op, or were somehow otherwise accounted for. I mean use your imagination. However this is likely a case where minimizing the necessary variables (that is, human beings being involved, and especially Pakistani human beings) provides better results.
Now, beyond the infiltration, where to start? Probably with human intelligence rendered from Gitmo and other locations as well as from analysis of scraps, bits, and bites taken from sites of…kinetic action.
And more? Back to the National Journal article:
A memo from CIA Director Leon Panetta sent Sunday night provides some hints of how the information was collected and analyzed. In it, he thanked the National Security Agency and the National Geospatial-Intelligence Agency for their help. NSA figured out, somehow, that there was no telephone or Internet service in the compound. How it did this without Pakistan’s knowledge is a secret. The NGIA makes the military’s maps but also develops their pattern recognition software — no doubt used to help establish, by February of this year, that the CIA could say with "high probability" that bin Laden and his family were living there.
What’s the NMA TV take on how things went down?