Keynote: everyone will probably have heard about Azure by now. Although this something that's a big deal for Microsoft from a business perspective, it seemed to lack the 'wow'-factor for developers. It will be interesting to see how the pricing will be. That'll be the biggest hurdle to get mainstream-adoption.
BB11 Identity Roadmap for Software + Services: open up the Active Directory-identities to the web using Geneva. AD-identities are translated to claims which can be used by anyone because it's all standards based.
BB09 Microsoft Office Communications Server and Exchange: Platform Futures: I actually did the HOL before this session. Using the managed provider there's very little left to do to build solutions like Automated Call Distribution.
PC21 ASP.NET MVC: A New Framework for Building Web Applications: control the html and separate concerns using MVC. Stackoverflow is using ASP.NET MVC.
TL17 WF 4.0: A First Look: the next version of WF boasts a 10-100x improvement in performance. Seems to be much improved in usability for the developer.
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