Phil Wainewright at ZDNet sees the potential in the API / Live platform:

"Most intriguing of all, though, is the mention of open APIs for the Live platforms. Perhaps I misheard this. Can Microsoft be seriously suggesting that partners and customers will be able to connect to these services from any platform, and mash them up however they like (subject to paying the required subscription fees or accepting the obligatory advertising, whichever applies)? I'm not sure that Microsoft really does have the nerve to carry this through, but it should: its consummate expertise at fostering developer ecosystems could really light a fire under its on-demand platform if it gets the API offering right. That would make today's announcement one of those landmark dawn-of-a-new-era moments: the day the great Microsoft mash-up began."