When you're deploying an ASP.NET website that uses the new Routing feature from MVC, you might run into a problem mapping the routes in Integrated mode. The documentation states that using Integrated mode on IIS7 doesn't entail any extra configuration, but in the odd case it does (throwing Error 404 on routed URLs but not .aspx paths), you can open up your web.config file and modify your <system.webServer> / <modules> tag:

<modules>
...
</modules>

... to something like this:

<modules runAllManagedModulesForAllRequests="true">
...
</modules>

Or, if you're not using modules, just put an empty tag within <system.webServer>:

<modules runAllManagedModulesForAllRequests="true" />

That forces IIS7 to always run all loaded web server modules, including URL Routing (inherited from the 4.0 application pool).