Microsoft has just released a new section of the MSDN web site for those developers upgrading from ASP.NET 1.x to ASP.NET 2.0. Check it out.
A couple of the articles I found most interesting:
My day job includes a mix of C# development on .NET 1.1 and 2.0 with most development moving to 2.0 in the near future. We use Telerik radControls for much of our ASP.NET user interface and Telerik has yet to give us a set of controls we can use with VS 2005. Once this occurs we will probably converting all of our existing ASP.NET 1.1 code to 2.0.