Yeah, cbean, that's a bug that I also came across -- it strips out anything that looks like an XML tag. That sucks, because assigning matched groups to variables is one of my favorite Ruby regex features!

Its because you probably aren't checking all of the test cases within irb.
This test case is failing:

# should == 'theStealthWarrior' but instead is returning 'TheStealthWarrior'
to_camel_case("the_stealth_warrior") 

This is still the same code.