In my understanding, which relies completely on the judgements of co-workers regarding the rails side of the debate, TurboGears is more flexible. Tasks which fall inside the scope of Rails' "opinion" are probably easier there, but anything outside of what Rails was built to do is harder than equivalent deviations from TurboGears. Obviously this amounts to little more than hearsay, but nonetheless I think it is an important element to look into.
I can say that each of them has their own genius decisions, and neither is so lacking in documentation or community support to preclude choosing either framework based on how well it suits your project. -- http://mail.python.org/mailman/listinfo/python-list
