Machine translation is improving, and as this article notes, will never replace humans. But the shear size of Google's computing power certainly helps it along.
Like its rivals in the field, most notably Microsoft and I.B.M., Google has fed its translation engine with transcripts of United Nations proceedings, which are translated by humans into six languages, and those of the European Parliament, which are translated into 23. This raw material is used to train systems for the most common languages.
Using Computing Might, Google Improves Translation Tool - NYTimes.com