Phlip on the The XP Yahoo! group writes a nice bit about Ruby v. Python (and along the way Perl). He references AlternateHardAndSoftLayers from the fabled C2 wiki in making a nice point about optimizing for scripting languages:
Dynamic languages and unit tests permit you to blaze through features and refactors. Without the requirement to maintain inheritance graphs just to substitute objects, and with deep support for containing objects and translating their types, these languages stay out of your way.
Command-and-control code does not require performance. Low-level inner loops do, so practitioners typically port to a C language as soon as parts slow down. This pattern (AlternateHardAndSoftLayers) allows Ruby and Python to ship with very powerful libraries, bundled with their default distributions.
This is excellent advice and another indication that the best programmers are also some of the most well-rounded. Being the world's greatest expert on FOO at the expense of knowing little else is not that useful outside of one-language/one-vendor closed shops.