Forrester's Charlene Li provides some food for thought regarding the Windows and Office Live and the opportunities for third parties:

"Q: Microsoft talked about having an open platform for developers. Is Microsoft really going to be open about this, or are they going to stick it to developers in the future?

A: This is by far the biggest deal in terms of the announcement, and probably the most poorly expressed part too. I believe Microsoft is fully embracing hosted services and supporting developers, and more importantly, now have different mindset in how they approach the market. Sure, they would still love to be central your personal and work life (that IS what Windows and Office Live are about, after all), but they know they can’t do it alone. This is especially true with Google and Yahoo! breathing down their necks. While not yet available, the APIs will allow developers to build on the Live platforms, leveraging all of the communication, payment, and identity systems that have already been built. Let’s take Office Live as an example – it will launch with 22 applications available for a subscription fee, and all of those applications are Microsoft developed. Developers could build a light app directly into Office Live and tap immediately into a broad audience. Moreover, there’s a built in revenue model, with users paying a few months more to get access to the service. Contrast that to a business enterprise software developer today who has to build everything pretty much from scratch – and then build a marketing, sales, and distribution organization on top of it as well. The outcome: we’ll see lots of innovation for a market that historically has seen been given hand-me down technology solutions. We’ll see the inevitable list of complaints from developers who want nothing to do with Microsoft – in fact, Robert Scoble listed 12 reasons why this is the case."