2008 was a pretty good year for the .NET world. We've seen a pretty big rise in people's interest, understanding and accepting of Object Relational Mapping, Inversion Of Control containers, writing testable code and separation of concerns. Those aren't the only things that have improved in the .NET world this year, but i think those are the most important improvements we've seen from the developer community.
I'm also pretty happy with the way Microsoft is starting to open up the development of some of their projects, with ASP.NET MVC being a very nice example. They're not doing true open source development yet, but at least they are listening to the community more and more. I'm especially happy with how people like Scott Hanselman, Phil Haack, and Glenn Block not only deal with the community, but are active (and positive) participants of it. Then again, there are definitely things that should've been handled better (Entity Framework, Oxite, LINQ To SQL's future, ...). Hopefully, we'll get to see a lot less of those kind of mistakes in 2009. But all in all i think it's been a rather impressive year from Microsoft's Developer Division.
2008 has been pretty good for myself as well. I escaped from working in Enterprise Hell and now get to do a lot of interesting things at work with motivated and talented co-workers. I've also seen my subscriber count go from 40 to around 700 (on average) this year, which certainly provides a lot of motivation to keep going. I also joined some great bloggers at ElegantCode.com, and joined the NHibernate developers. Should keep me pretty busy in 2009 
I'm taking a few days off from blogging, so happy newyear everyone, and i'll see you all early January