Install all of the Google Web Fonts on OS X via command line (webfontload.com)

Or alternately you could do a

   hg clone https://code.google.com/p/googlefontdirectory/

... and skip the part where you have to run a random shell script curl'ed off the Web.

(At least in this case the random shell script isn't demanding you run it with elevated privileges, though. +1 for that.)