Wow - Google and searchers were all over the "URI templates and hackable search engine friendly URLs" line in my short WPF post below, which means there's a lot of interest in URI templates.

I found this post on Creating a Template based URI very helpful. You DON'T have to be building a WCF service to use these. You MUST however include a reference to the System.ServiceModel.Web assembly in your project before you can use the System.UriTemplate type.

Scott Hanselman's presentation at MIX08 on MVC was also very helpful as well as it clarified many things (not to mention being hugely entertaining).

The URI Templates of .Net 3.5 don't have anything to do with REST - they're just a utility class that helps to bind and match templates and parameters to and from URIs. When combined with a URL rewriter they make it easy to present hackable URLs the world.  As Scott said in his presentation - the URLs in a browser window are effectively part of the UI - and so should be treated accordingly when possible.

So... mystore.com/clothing/shirts would be cool, as opposed to mystore.com/products.aspx?type=clothing&category=shirts