Microsoft loves open source for the same reason IBM loves it, for what it can do for Microsoft.
Microsoft has used its patents, just as IBM did, to bully its way into the space, it has created open source licenses the suit its needs, and it can use open source as a glue to hold customers to its products with their cash flow. It can now afford to be magnanimous.
What's not to love?
Once more we have to explain to our fellow typists the difference between open source and FOSS. Open source is a practical means for doing business. FOSS is an ideal.
Open source does not mean you wear a hair shirt and abjure filthy lucre -- just the opposite. (As if FOSS ever did. There are far more long-haired rednecks out there with Bush-Cheney 2004 stickers on their trucks than hippies. This is 2010.)
Of course just because Microsoft loves open source that doesn't mean it does what the open source movement wants it to do as opposed to what Microsoft wants to do. Microsoft loves open source because it has found a way to twist it in the direction of its own self-interest.
It is also in Microsoft's self-interest to appear benign toward open source right now. Oracle has gleefully taken up the mantle of open source villain, and Microsoft's new public stance may help it take some business away from its rival.
In the age of cloud computing, a completely proprietary stance makes no logical sense anyway. Where the software comes from does not matter to the cloud user. All they care is that it rains applications. Profitable ones.
Now there may come a time when it will be in Microsoft's best interest to hate open source. And the fact that it loves open source doesn't mean it won't compete fiercely against open source, and try to take business away from open source companies.
It's not love as in "I will always be true to you." It's not a marriage. It's a relationship, a guy thing. More like, "I love you, man," and punching open source in the shoulder after a few extra beers on a Friday night.
We are talking about the love Pete Townsend sang about in "Behind Blue Eyes." "If I shiver please give me a blanket, keep me warm, let me wear your coat." That's a groovy kind of love, too. But I won't get fooled again by it.