Wow, that is unexpected. I can think of a lot of developer tools that use google translate to give a rough first translate. Things like Wordpress and web framework plugins. It seems like they should have just dropped a fee structure on top of it and that would eliminate abuse.
If any developers out there are looking for a new API to target, you could consider mygengo. It's not free (because it isn't machine translation), but they do have developer tools and an API available: http://mygengo.com/services/api/
That said, we definitely welcome developers to our services. I just wanted to take a second to note this for any Python developers interested in our services, though - if you don't like the supplied Python library (I didn't), I wrote a new more concise and documented version. It's easier to follow and extend, and has some functions to help with encoding/decoding characters.
We're considering adopting this as the main Python library in the near future. Always interested in input from other developers!
If any developers out there are looking for a new API to target, you could consider mygengo. It's not free (because it isn't machine translation), but they do have developer tools and an API available: http://mygengo.com/services/api/