Microsoft has just released it’s October 2009 release of Silverlight 3 Toolkit. You can download it from: Silverlight 3 Toolkit October 2009 Installer. Also have a look into the sample application at: Silverlight 3 Toolkit Sample Application
Silverlight 3 Toolkit has now full design time supports for Visual Studio 2010. Charting tool has been changed. They now introduced ISeries interface as the base interface for all the Series & StylePalette now renamed to Palette. So, those who are using StylePalette just make those changes in your code. You can now customize the LegendItem very easily. Silverlight team now added the support to Themes for Accordion, DataForm, DataPager, GridSplitter & ChildWindow. Added support for Drag & Drop functionality for some common items like ListBox, TreeView, DataGrid and Charting tools. Moreover the mousewheel support has been now added to navigate the GlobalCalendar & TimePicker controls.
Have a look into those latest features of Silverlight 3 Toolkit. In real scenarios those are really very awesome features. Though it is their 5th release of Silverlight Toolkit, hope they will come up with lots of required controls in the future versions.