Asked why it took so damn long to get from Windows Mobile 6.1 to 6.5 (which there isn't a whole lot of difference, honestly), Robbie Bach says that the shift from a business focus to an all-around one, was huge, and took a lot of time.
But, from here on out, he says that with Windows Mobile the "pace of innovation is gonna accelerate dramatically going forward" so you're going to see a "set of speedy innovations from us over the next 6, 12, and 18 months."
We really hope so.