Bruce Eckel (author of amongst other popular books 'Thinking in Java')
has doubts why anybody would switch from Python to Ruby. An interesting
read:

http://www.artima.com/weblogs/viewpost.jsp?thread=141312

To quote him:

"The person I want to hear from is the core Python expert, someone who
knows that language incredibly well, who has decided that Ruby is just
so much better that all the mature Python libraries and community
expertise doesn't hold a candle to the value of moving to Ruby. That
person would be able to make a compelling, feature-by-feature argument"

Any Python experts here? :)