Working on implementing TFS throughout our organization. It is easy to integrate with .NET
projects and any platform that uses Eclipse or a derivative of Eclipse f
Xcode integration is something that we at Teamprise have been looking into a lot. One of the main problems for us is that Apple does not provide a version control API that we can hook into to add a new version control system to Xcode - for integrated version control it is either the systems that Apple provide access to or nothing at the moment.
That said, we do have a number of customers who develop in Xcode for TFS. They either use Teamprise Explorer (which is a standalone GUI client to TFS compiled as a Universal Binary) or they have macros inside Xcode that perform basic check-out and get operations in-conjunction with the TFS command line (tf). It's obviously not the ideal experience but acceptable for them. The stand-alone GUI has the advantage that you can do all the work item tracking stuff there as well and integrate this with your check-ins.
Sorry if this is a very "marketing" type answer - just trying to let you know what our current customers do with Xcode. If you want more details around the macro approach then let me know.
Hope that helps,
Martin.