I have been studying WPF more seriously for about two months. It is an amazing technology with a lot of new concepts that may be hard to grasp at first. In order to help others that may be trying to learnWPF and don't know where to start here is my take on it.
Although there is a lot of good material on the Internet the best way to learn (in my opinion) is still a good book. I have browsed through few books:
I found that the best one to get started with WPF and to read from cover to cover is Essential Windows Presentation Foundation by Chris Anderson. It is a relatively short book with about 500 pages. You will find that it is really easy to read with good examples and direct explanations. I have to say though that this book is not a good reference book. Don't let the fact that this is a 2007 book scare you away, this one is all about concepts and those didn't change since version 3.0 of the framework.
The other book I really liked was Pro WPF in C# 2008. This one is a in depth dive into WPF and maybe is not the book you would want to get started with. On the other hand this is the best reference book. It is really easy to browse since it has a dedicated chapter for each topic. Actually, this is the only book among the ones I looked at that has this format. The other books try to group related topics in the same chapter, which makes a good read but harder tolookup a specific thing.
The other book I would recommend is Windows Presentation Unleashed. It has an in depth coverage of all topics and is really easy to understand. The only thing I have against it is that it is a bit outdated since it was written for the framework 3.o. I wouldn't by this one but if you have someone you can borough from then I guess it isok.
There is also really good material on the MSDN site. Many of the books I mentioned before are heavily based on this documentation. The books are still more friendly to read but if you are looking any one topic in special the MSDN documentation is a really good place to search. Here is the link.
After you have a clear understanding on concepts such as Dependency Properties, Routed Events, Commands and Binding you have to look atMVVM concepts. This makes WPF even more amazing. I recommend getting started with Josh Smith's article on the MSDN Magazine called WPF Apps with The Model-View-ViewModel Design Pattern. Also make sure you follow the WPF Disciples.
If you are the screencast type of guy (or gal) you can checkout a lot of great videos on the WindowsClient.net site. Make sure you go to the Learn section.
Well, I think that is it. I'll update this post if I remember anything else but for now I think that this is plenty of material for you to get on your way to becoming aWPF master :-).