Below you will find my presentation slides and demo files for my SharePoint TechFest 2010 presentation on Exposing an MVC Application through SharePoint.  One of the points I forgot to mention goes back to the performance and licensing benefits of this approach.  If you have a SharePoint box that is completely slammed, you can put the MVC application on a separate web server and essentially offload the application processing to another server.  In terms of licensing, you can leave SharePoint off that new server and just access SharePoint data via web services from the box.  This makes it a lot cheaper if you have MOSS - but if you're just running WSS then it may not have as many cost benefits.  Remember, programming against the web services is not always the easiest thing, so you have to weight the cost/benefit ratio when making such a determination.