I'm a passionate Pythonist with a deep respect for Ruby. I personally find Python to be extremely elegant in both syntax and paradigm, but Ruby is the next thing I'd use if Python were to disappear today.
In my experience, Python generally has more backend libraries and tools, while Ruby has more frontend. Of course, there are hundreds of exceptions to this, but the premise of what I'm saying is this: Python developers tend to come from other unixy backgrounds, and Ruby devs often are web-centric.
As far as the frameworks themselves are concerned, Rails has a bit more magic "convention over configuration", while in Python "explicit is better than implicit", so Django is a little more engineer-friendly.
I highly recommend you read the Zen of Python to see if the language is a good fit for you: http://www.python.org/dev/peps/pep-0020/
Something to keep in mind.
On yet another note, Pythonists are in HIGH demand. Good Python devs (who aren't actually Java devs who've dabbled with Python once or twice) are hard to come by. Excellent job opportunities because of it.