FWIW, Currently, the iOS project created by Introjucer has the CoreText Framework linked in as “required”. This means that Deployment Targets below 3.2 won’t work, because they will crash at app load. Usage of CoreText is conditional in the code itself, but the linkage is not ‘weak’.
To build for running on a 3.1.2 (original iPhone) device, I changed CoreText to ‘optional’, set the Deployment Target down to 3.1, and added armv6 to the Architectures. I haven’t looked closely, but I believe that introjucer is using “standard” for arch, which, on XCode 4.2, now means armv7 only.