Accessing static content of an ASP.Net MVC project with IIS7
The problem was permissions. Even though when I create the IIS7 web site I told it to access the files as my user (it wouldn't work at all otherwise), for static file it was using the user of the application pool. Giving access to IIS APPPOOL\MyApplication to the folder where my project was fixed the issue.
I had to take the additional step of adding read permissions to the IUSR account as detailed in this post: http://forums.iis.net/t/1175217.aspx