I added a link to the sidebar of my SDL OpenGL article that contains a version of the project updated for Xcode 4.1. The original project had several problems building on Xcode 4.1 that persisted after I modernized the project. The updated version of the project works on Xcode 4.1 and uses the Mac OS X 10.7 SDK. I have not tested the project on Xcode 4.0, but at a minimum, you must change the Base SDK to 10.6 to get the project to work on Xcode 4.0.

The original project is still there. I just added another version to make things easier for people using Xcode 4.1.