WPF has a learning curve
Karsten hits the nail on its head with this post about the WPF learning curve. No doubt that WPF is a very powerful framework indeed, when you start simple you feel productive but as you dig deeper and deeper the curve gets steeper and steeper. As he points out a lot of WPF will feel in some ways a lot like what you have used before and in many ways has concepts that are also very new to you. I agree that claims that WPF makes you productive in x weeks when it really takes months to have a solid understanding of WPF. At the moment WPF is so new that it lacks the time to have developed resources in books, articles and websites etc, Chris Sell's book is the exception and I fully recommend it for anyone new to WPF.
Tim has a list of WPF blogs that have some great posts on how to do things. Lastly I recommend folks look at tools like
Expression Interactive Designer, I learnt to code WPF by hand first and then looked at tools like EID. You can do the reverse however, be productive in EID and look at what code it genereates to get comfy with the concepts and tweaking that code by hand. Sure WPF has some very advanced concepts that will take an advanced WPF book or website to help lessen the curve in that area however I recommend the forums (if your new to WPF I also recommend this) as many of the guru's and Microsoft folks hang out there and will give you a hand.