Excuse my 2¢, but I really don't like ads like this that make the language the main skill. Python is obviously your selected tool of expressing the ideas and the demands of the job, but if you express no demands regarding any domain specific experience. This makes the job sounds very shallow, and you will likely put off lots of applicants.

One of the beauties of Python (and that goes for lots of other modern dynamic languages) is that it adapts itself to an extreme variety of tasks. E.g. it is the selected tool by the professors of the ongoing AI course at Stanford. I'm using it for data visualization and testing out various algorithms. My company is using it as the embedded tool for writing test and calibration scripts for our machine. You can find thousand other uses on the net.

For a serious job you need someone dynamic who has the mental abilities to solve your problems. Preferably she can already express these ideas in Python, but if the applicant turns out to be highly skilled but e.g. currently is fluent in Ruby or Haskell, you'd be a fool to turn her down.

But on the other hand. Perhaps you just need someone to write test scripts to your existing system. But then say so!

Regards,,
Dov