Here are some of the latest updates to the WPF documentation that you might want to check out.
- What's New in WPF Version 4
- DataGrid has improved content including a new walkthrough, Display Data from a SQL Server Database in a DataGrid Control
- You can take advantage of the Windows 7 taskbar in WPF applications using the TaskBarItemInfo and JumpList classes.
- The WPF Designer has new features highlighted in walkthroughs on Creating a Data Binding and Using a DesignerInstance to Bind to Data.
- WPF provides support for touch applications. See Walkthrough: Creating Your First Touch Application