Sometimes going back to the basics is the best path. I just grabbed the python-mode.el 6.1.1 release from the python-mode.el launchpad site, which is maintained by some folks who use Python on a frequent basis. Fired up the mode and the current implementation seems much more consistent than some of the current new kids on the block, including Emacs 24.3’s built-in Python mode.
Even better 6.1.1 has support for virtualenvs.