You might hear this operator referred to as a "hash rocket," meaning you use it when defining a ruby hash.
This is the Ruby Hash documentation, if you're not familiar: http://www.ruby-doc.org/core/classes/Hash.html
Note that in Ruby 1.9, if you're defining a hash that uses symbols as keys, there's now an alternative syntax available to you: http://blog.peepcode.com/tutorials/2011/rip-ruby-hash-rocket-syntax
