I'm trying to come up with a good coding problem to ask interview candidates to solve with Python.
They'll have an hour to work on the problem, with an IDE and access to documentation (we don't care what people have memorized). 
I'm not looking for a tough algorithmic problem - there are other sections of the interview where we do that kind of thing. The point of this section is to sit and watch them actually write code. So it should be something that makes them use just the data structures which are the everyday tools of the application developer - lists, hashtables (dictionaries in Python), etc, to solve a quasi-realistic task. They shouldn't be blocked completely if they can't think of something really clever.
We have a problem which we use for Java coding tests, which involves reading a file and doing a little processing on the contents. It works well with candidates who are familiar with Java (or even C++). But we're running into a number of candidates who just don't know Java or C++ or C# or anything like that, but do know Python or Ruby. Which shouldn't exclude them, but leaves us with a dilemma: On the one hand, we don't learn much from watching someone struggle with the basics of a totally unfamiliar language. On the other hand, the problem we use for Java turns out to be pretty trivial in Python (or Ruby, etc) - anyone halfway competent can do it in 15 minutes. So, I'm trying to come up with something better.
Surprisingly, Google doesn't show me anyone doing something like this, unless I'm just too dumb to enter the obvious search term. The best idea I've come up with involves scheduling workers to time slots, but it's maybe a little too open-ended. Have you run into a good example? Or a bad one? Or do you just have an idea?
I don't know about Python specifically, but I found that interview questions which involve recursion are a very effective filter. I have asked candidates to produce all the permutations of a string (and think about how to test it), and I have been asked to pseudo-code the Longest Common Subsequence.
Python coding test problem for interviews