Wally is at it again (finally). He just released his latest podcast after being away since mid-August. Anyway, his podcast is about a new feature in ASP.NET 3.5 SP1 (formerly the ASP.NET 3.5 extensions) called Routing. Routing can be done using System.Routing, ASP.NET MVC, or 3rd party plug-ins such as NVelocity. Check out this podcast to find out more:
http://aspnetpodcast.com/CS11/blogs/asp.net_podcast/archive/2008/10/07/asp-net-podcast-show-125-routing-with-webforms.aspx