They say that they used Google Trends to find out which articles people were viewing most from India, the Middle East and Africa. Quote from the Google Blog:
"We believe that translation is key to our mission of making information useful to everyone. For example,Wikipedia is a phenomenal source of knowledge, especially for speakers of common languages such as English, German and French where there are hundreds of thousands—or millions—of articles available. For many smaller languages, however, Wikipedia doesn’t yet have anywhere near the same amount of content available...
...We began these efforts in 2008, starting with translating Wikipedia articles into Hindi, a language spoken by tens of millions of Internet users. At that time the Hindi Wikipedia had only 3.4 million words across 21,000 articles—while in contrast, the English Wikipedia had 1.3 billion words across 2.5 million articles."
Wow, translating to such less used (on the web) languages will be a tiring job. I hope Google can do it single-handedly.
Originally from the Official Google Blog.