If you're a WPF developer, check out the WPF Toolkit up on CodePlex. There were a few goodies announced yesterday at the PDC which were posted there, including:
- V1 of the DataGrid
- New DatePicker/Calendar control!
- Preview of VisualStateManager (VSM) for WPF (compatible with the VSM in SL)
Also, a link to the WPF Ribbon Preview appears there as well.
For WPFies, it's good to keep an eye on this project, as the product team uses it as their outlet for new ideas and preview bits.