hmm there's some interesting stuff there...
Easily solved by the typical XCode user. I don't think you're properly visualizing the level of cluelessness of the would-be consumer of a pre-made Arduino sketch. "rename main.cpp to foo.pde in a directory name foo, and put all the other file there too" just has SO many things that could go wrong.
To me, it seems this point of view is a little bit overly cautious towards the "beginner Arduino User".
We were all beginners at a certain time and I think this little challenge of renaming a main.cpp file into a project_folder_name.pde file is only a small step to make you learn something new. Compared to learning about pointers, inheritance or even functions, renaming a file seems like a piece of cake. (mmm.. cake :-))
Before I started this effort to try to make an Arduino project with XCode, I had no knowledge at all about makefiles. Just by doing this I already learned so much about this completely new topic. It's fun! And it's a great way to learn too: trying to take this next step and looking through other people's code trying to make sense of it...
It's great that the Arduino IDE is working so good "out of the box" so beginners can get their hands dirty immediately. But at a certain point, if you want to create more complex programs you'll want to learn about classes, pointers, etc and then it is actually a good thing to have a more advanced software community that can happily program in their "professional" IDEs and assist those people.
But what if the Arduino IDE would allow correctly formatted C/C++ code? Then there would be no compatibility problem anymore, right?
I feel we're getting a little bit off topic here.. this thread was going to be about getting XCode to compile Arduino projects I believe.
So let's first get the templates ready for XCode 3.2.x and XCode 4.x and all the different boards, get them properly working for everybody and then worry about the potentially more complex problem of compatibility with the Arduino IDE.
If you have any suggestions on how to solve this problem, let's hear 'em! Maybe there is a very simple solution that I'm not seeing right now... like a simple text file included in the XCode template that explains what to modify for use in an Arduino IDE and vice versa?