I've just released for the first time six, a set of helpers for maintaining a code base on Python 2 and 3 simultaneously. It includes fake byte and unicode literals and wrappers for syntax changes between the languages. The license is MIT.

You can download it on PyPi: http://pypi.python.org/pypi/six or read the documentation: http://packages.python.org/six/

Bugs can be reported to the Launchpad page: http://bugs.launchpad.net/python-six