可以在“ASP.NET Web应用程序”中进行动态编译吗？

Can I somehow utilize the App_code folder in a web application project to compile code on the fly? It'd be great for plugins. Recently Rob Conery demonstrated its use in his talk at MIX 09 in a ASP.NET MVC app. I tried to do the same in a web app but I can't access the classes under folder in a