There are a number of reasons for Microsoft doing this move. One of them being that this year all the H1B visas were distributed within the first day the season was open. The ICE doesn't start accepting applications until April for an October distribution, but it is next to impossible to get a H1B visa if you are a for-profit company.

Microsoft will likely hire a number of Canadians (they certainly have imported quite a few into the US facilities).

If nothing else it is alot of well paying jobs...