If the leaked documents are right, developers are "expected to leverage Microsoft's growing stable of cloud services," which means they will rely on the newly-born Azure services which again haven't had much road testing time. I also wonder how much of that expectation is baked into the development environment. If the developer decides to use other web-based services instead of Azure, do things get significantly harder?
If there is any disappointment in what's been revealed so far, it is that Microsoft seems to be ignoring standards and instead building its own proprietary world. I am a big supporter of web standards; much of what Silverlight does could be accomplished instead with existing standards like HTML5, AJAX, and JSON. That would have allowed developers to take advantage of their existing knowledge and even existing code -- but it requires a browser that supports standards. With all the other work to be done for Windows Mobile 7, will Mobile Internet Explorer be ignored in favor of the new proprietary native environment, snubbing web developers who prefer cross-platform standards? If so, it's a loss for both users and developers.
This additional information shows that Microsoft is planning an incredibly ambitious set of changes with Windows Phone 7. Perhaps this is a Hail Mary pass with a low chance of success, but it's actually encouraging that the company can still work up the courage to take major risks to recover a leadership position in the market. Microsoft will need to deliver a massive amount of technology to make it happen, then motivate developers to finish applications so that the product can launch this fall with more than just a promise of things to come.