CNET has reported of Microsoft plans to open up the up the APIs for developers to build new, cool stuff upon MSN and other Microsoft online properties.  Although the article describes the move as taking an aim at Google, I think it is really much more than that (disclaimer - I'm not part of team involved in this strategy, so take my view with a pinch of salt here)

It's all about opening up, setting the data, the methods and much more free for others to innovate, create and play with - not just within the search space - this bigger than Microsoft competing with a single competitor.  Yes,
perhaps Google has acted as the catalyst (of course we want to compete with Google) but the implications, depending on how far Microsoft goes and how speedily it can get there (clue: http://msdn.microsoft.com/msn, via Dare) are potentially profound.  There are plenty of others already making the same journey and benefiting.  Virtual Earth hacks are just the beginning...baby steps.  This broader Microsoft Web Platform move could hasten Microsoft's and its associated properties, partners and customers move to the inevitable next-destination - Web 2.0

Richard MacManus reacts to the move at his new (and impeccably timed) blog at ZDNet, 'Web 2.0 Explorer'.  His take is worth a read:
"Microsoft's Web platform is though at least a sign that they've moved on from trying to make Windows the dominant platform for developers to build on. Although it'll be important to keep a strong developer presence in Windows, Microsoft recognizes now that the Web is really where the developer action is and so they have to join the party."
(See, "I once had a dog and his name was Bingo!")...Sorry, Richard goes on:

"I don't think the Web platform is Microsoft's primary strategy for its future survival, by any means. But it's an important acknowledgement that the Web is the place to be for both developers and consumers. As for how its customers access the Web, well that's at the heart of Microsoft's strategy for Web 2.0. If they can't own the platform, they want to own as many of the paths onto the platform as possible."

, roll on.

(The next week Microsoft web platform announcements at PDC should be most interesting - catch BillG's keynote live on the 13th Sept (8:30am -08:00 GTM) if you can.