During PDC atleast 2 of my talkes revolved alot around Web 2.0 architecture, REST, POX, AJAX, Mash-ups, Composite apps etc. Web 2.0 is already out there and we are not really planning for the future on this node. As with any other paradigm or technological advancement, the most important thing to consider is Architecture. Its Architecture that dictates how the paradigm or technology will affect the system. Its true that most of the people are worried about impact of Web 2.0 on their enterprises. Keeping the same context in mind I would say that ther couldnt have been a better time for the release of 12th MS Architect Journal that focuses of Web Architecture. I would say its a must read for any one interested in Architectural side of Web 2.0. You can download your free copy here