In this post, Laurent Duveau talks about the Telerik Assembly Minifier which helps you to reduce the size of your Silverlight xap and he gives a good example on how to use this tool.
If you are using Silverlight controls from the Telerik suite, you’re going to love this.
Telerik provide a new free tool to help reduce the size of your Silverlight xap. The Telerik Assembly Minifier can be found here: http://minifier.telerik.com/