URL Routing with ASP.NET 4.0 fully supports postback scenarios.  The <form runat=”server”> control will automatically emit the same URL that caused the page to be rendered.  For example, if you access a page with a /products/software URL then any server-side <form runat=”server”> control within it would render out a <form action=”/products/software”> HTML element back to the client – which means that any postback scenarios that happen on the page will preserve the original URL. 

This makes supporting clean, SEO friendly, URLs easy with Web Forms and postback scenarios – and avoids some of the tricks people need to use today when using URL rewriting modules to achieve similar effects.