How do I detect a mobile browser in a .NET MVC3 application

MVC3 exposes an IsMobileDevice flag in the Request.Browser object.

So in your razor code, you can query this variable and render accordingly.

For example, in your view (razor):

@if (Request.Browser.IsMobileDevice) {
  <!-- HTML here for mobile device -->
} else {
  <!-- HTML for desktop device -->
}