I’ll be brief.
Blizzard Watch just posted a great analysis of the iteration times for all the past expansions. I took that data and visualized it.
Blue is the gap between the release of the previous expansion and the announce of the new one; red is basically the time between that announce and the start of beta; and the orange is the length of the beta to release.
Crunch it however you want, but the big takeaway for me is the damned heroic effort in getting MoP out in less time than all but one previous expansion, and that’s INCLUDING a total refactoring of The Jade Forest.