The Activision 10 year deal with Bungie has come as a surprise. However, given the outline of the partnership, Microsoft's statemented response doesn't.
The deal states that Bungie and Activision/Blizzard "have entered into an exclusive 10-year partnership to bring Bungie's next big action game universe to market."
Microsoft's statement to the press reads:
"Our partnership with Bungie as a first-party developer for Xbox 360 remains unchanged, and right now we're deeply engaged with them on the development of Halo Reach, which is poised to be the biggest game of 2010."
Next up, EA brings congratulations?