It looks like I'm going to be presenting the Web Developer content at the Belfast launch next week, in addition to another riveting performance of the keynote demos! So I've turned some of my thoughts back to ASP.NET 2.0.
I still think the Provider model -- which handles high-level concepts like site membership, roles, and personalization, but allows you to modify the way they work at a low level by swapping in and out new providers -- is one of the coolest new things.
For the majority of cases, the default providers, which work with SQL Server 2005 Express Edition, will do the job. But for the folks who want to build their own provider implementations (to do something like tweak the provider behavior to interop with legacy systems), ASP.NET guru Scott Guthrie pointed out some great online content a few weeks back. 120+ pages of good word-content, and working C# sample implementations of the various provider types (usually going against an XML or text file for persistance).