Developing mobile web sites is a hot topic at the moment. Steve Sanderson has written a great article titled "Add Mobile Pages to Your ASP.NET Web Forms / MVC Application" over at ASP.NET explaining exactly how to start. The article explains clearly how to create mobile web pages as part of a wider application. The 51Degrees.mobi Foundation product available via Codeplex and Nuget is used for device detection with both MVC and ASP.NET Web Forms.
Steve's also written about MVC 3 and mobile browser detection on his personal blog at stevesanderson.com. This is worth a read for those considering an MVC approach to mobile web sites.
All the team at 51Degrees.mobi are delighted the project has been recognised as a useful and complementary tool for mobile web development.