We just refreshed the online docs for Silverlight 3. In addition, the offline CHM has been updated. Most of the updates were just doc bug fixes. Right now writers are mostly focused on documenting Silverlight 4 Beta features (of course SL4 Beta hasn't released yet). 

IMPORTANT! If you open the CHM and cannot view content, do the following to resolve the issue:
- Right-click the CHM file, and then click "Properties".
- Click "Unblock".
- Double-click the .chm file to open the file.

Sam