Is there a blog/forum/listserv that is equivalent to RubyQuiz.com for the Python language?
At the risk of stating the obvious, why not just do the rubyquiz examples in python. Those exercises as well as others aren't tied to a language - you're just as well off just doing projecteuler problems in python rather than searching for python-specific puzzles. A puzzle is a puzzle a language is just a tool to solve it.
Ruby Quiz for Python