Microsoft documentation fail
Before it sounds like all I do is complain, let me first say that the advances in C# 3.0, along with LINQ and ASP.NET AJAX, have made programming more fun than ever. I've spent a lot of time lately using all of this stuff on my own projects, and I'm having a great time. I'm going to make some lucky employer very happy (or annoyed because they're still using v1.1).
That said, the documentation situation is bad. It's better than it was circa 2004, but all of the rapid shipping and fragments of the .NET world are leaving the docs a mess. It starts with the MSDN site itself, which has much better search than it used to, but is still heavy and slow because of the treeviews. It also doesn't look right in Firefox, and doesn't retain your preference for programming languages.
The ASP.NET site (which, by the way, also beachballs Firefox on the Mac with every page load making it unusable) has the outline of the new features in v3.5 SP1, and presents you up front with video. Video is not particularly useful when you want to just get to the examples. I go to the link for the browser history feature, and, after the five second beachball, see nothing but a video. OK, so where is the link to the docs? I had to watch the video (which is painful because it's VB.NET, and the presenter is "rusty" on his VB), and then see that it involves using ScriptManager, so I finally can go to MSDN and look up the right methods. I get there and find no examples of how to use the history point related stuff. Lots of wasted time. I end up having to rely on Googling third parties for a decent reference.
I'm a huge fanboy of Microsoft's, but this kind of thing frustrates me. I think the company needs a new role: Barrier Detection Monitor. This is a person who, in their product group, would look for things that make it harder for people to use the product. Too often there's something brilliant coming out of Redmond and it doesn't get the use or attention it deserves because of some kind of silly barrier.