You'll need to uninstall all Silverlight 2 Beta 1 tools, and install the Silverlight 2 Beta 2 Chainer (which includes tools for VS 2008, see www.silverlight.net)

Then update your Silverlight Dynamic SDK.

If you are doing Deep Zoom, get the new Deep Zoom Composer.

Here are updated Demos:

Demos 1 - 3

IronRuby Deep Zoom Sample