If anyone needs more proof that WPF is rapidly becoming a very mature platform, the level of articles that appear on CodeProject these days have long outgrown the 'Getting Started with Databinding'-level and are focussing more and more on design-topics like patterns and other enterprisey stuff.
As always, Josh Smith fulfills his pioneers' role in this whole thing, and posts stuff like Introduction to Attached Behaviors in WPF and Simplifying the WPF TreeView by Using the ViewModel Pattern.
This kind of articles goes way beyond the 'eye-candy only' stuff Microsoft used as the original selling point of WPF! This point has been brought up in earlier discussions about whether or not WPF is ready for LOB applications. It's really a shame the focus was more on the fact the you could now do radient gradients and animations without any difficulty and less on the great other features such as RoutedEvents and Commands.
Although these fancy features were enough to kindle interest from a lot of people, unfortunately these people were not so much into Enterprise Application development. So, when pondering which platform was most suited for their new application WinForms 2.0 or ASP.NET 2.0 was selected. I think the perceived lack of maturity in WPF and the exposed 'frivolity' of the platform played a large part in this (next to the -very real- steep learning curve).

This is part 2 of an pretty interesting series about Newton Physics extensions and Blender; I'm a big Blender fan (have you seen Big Buck Bunny? If not, go get it) so I'm excited to see it being used this way. The series is still in development but already you can get a good idea of the possibilities!

Lester has posted about his new update to XamlPadX, which is a nifty WYSIWYG (this acronym might be slightly anachronistic these days) editor in which you can test your XAML-snippets.
It works like a charm -it doesn't have Intellisense but then again, it's not meant as IDE, it's meant for Copy-Paste- and shows you the VisualTree of your XAML as well as all properties on your elements. It verifies your code and lets you know if you mistyed an element-name! All in all pretty handy.

Dr. WPF -congrats on the 1 year anniversary btw- posted an awesome article on CodeProject, called Introduction to D3DImage. It's a neat easy-going intro to one of SP1's improvements to the framework.

I'm a big fan of Visual Studio code snippets and keyboard shortcuts. So I really like typing prop followed by two tabs to quickly generate a property.

Today I found out a new one, specifically for WPF: propdp followed by double-tab gives you a Dependency Property and generates the following code:

public int MyProperty
{
get { return (int)GetValue(MyPropertyProperty); }
set { SetValue(MyPropertyProperty, value); }
}

// ... comment ...
public static readonly DependencyProperty MyPropertyProperty =
DependencyProperty.Register("MyProperty", typeof(int), typeof(ownerclass), new UIPropertyMetadata(0));


You can fill in some fields, such as the type and the ownerclass, but besides that you don't have to type anything.