Breaking Changes in Silverlight 2

There is an MSDN article that focuses on changes that might cause your older Silverlight ^[1]-based applications to now fail or behave differently not on new features/enhancements for this release:

• Important! Migrating Older Code to the Newer Release

• Update Silverlight.js

• Template Breaking Changes

• Error Messages May not be Available

• 2-D API Changes

• HttpWebRequest/HttpWebResponse Supports New Functionality

• PresentationFrameworkCollection Change

• Mouse and Keyboard API Changes

• Changes to TextBlock and its Helper Classes

• XML DTD API Changes and Default XmlResolver

• XamlReader.Load() Requires xmlns

• Removal of Managed FontSource (downloader) Signature

• XmlResolver Changes

• Assembly Changes

• Regenerate Web Service Client Proxies

• WCF JSON Services May Need SOAP Endpoints

• In Visual Studio, Use "Add Service Reference" Instead of "Add Web Reference"

• Loaded Event Signature Change

• Removal of Managed Downloader

• BrowserHttpWebRequest Removed

• Removal of managed MediaElement/Image.SetSource(downloader, partName)

• SetValue Changes

• Miscellaneous API Changes

• System.Net.Sockets Namespace Added

Read full Breaking Changes in Silverlight 2 ^[2].aspx) article.