cPickle is in the Python 2.7 standard library...
Yes and no. Pickle and cPickle are functionally the same thing, the difference between them is that Pickle is written in Python, whereas cPickle is written in C, and therefore of course faster. The problem is, the availability of cPickle is platform dependent. You don't have a cPickle implementation on every platform where a Python implementation is available. If you want to write truly platform independent python code, you can't rely on having cPickle at your hands.
That doesn't mean you can't use cPickle where it is
available. You just have to write your code in a way that makes sure to use Pickle, if cPickle isn't available, instead of throwing an exception if the "import cPickle" statement fails. Usually this is done something like that:
import cPickle as Pickle
...and you're on the safe side
That said, cPickle should be available on all platforms FO is currently developed for (Windows, OSX and Linux). Still, you should take the safe road and use cPickle as described above. It's simply the right way to do it.