I wonder what led to this.
I don't. Apples products have been slipping, and they've lost big leads in design and innovation to Google. Maps and iOS6 were big signs of that, probably catalysing the process.
Bringing online services together is good; Apples backed has been showing strain lately (game centre, Siri). Bringing them together with icloud makes sense.
Browett hasn't got Apple retail. He had to go.
Forstall is the biggest drop; he was widely seen as a long-term successor to Jobs. iOS has been sputtering recently though, and the skeumorphic design hasn't won any fans. He probably had to go for political reasons and for apparently not getting on well with the rest of the executive team. It'll be interesting to see if Federighi can step up to this enormous role, but I bet well be seeing hints of Ive in iOS 7.
Bob Mansfield is back. Best retirement ever.
In all, great shakeup. Hope to see this rejuvenating Apple. They'd gotten a bit old and Microsofty lately. Hope to see them going back to their strengths.