I just released WP7CertInstaller on codeplex to demonstrate a simple approach for installing Trusted Root certificates on Windows Phone 7.  This enables developers to use self-signed SSL certificates as is typically done in dev and test environments.

You can find the release at:

http://wp7certinstaller.codeplex.com/releases

Be sure to read my post on the WP7CertInstaller prerequisites and then my post explaining how the code works.

Enjoy and please let me know what you think!