Facebook co-founder and CEO Mark Zuckerberg at Facebook headquarters in Palo Alto, Calif., in 2007. The company is expected to file papers for an initial public offering this week. Paul Sakuma/AP hide caption

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A visitor looks at a Citroen diesel engine at the Geneva Motor Show in Switzerland in 2010. Diesel is popular in Europe but not the U.S.; now, automakers are giving the technology more consideration as a means to meet new fuel economy standards. Martin Meissner/AP hide caption

itoggle caption Martin Meissner/AP

A sign for Google is displayed behind the Google Android robot at the National Retail Federation in New York. The announced changes to Google's privacy policy have drawn both positive and negative attention. Mark Lennihan/AP hide caption

itoggle caption Mark Lennihan/AP

Facebook CEO Mark Zuckerberg shows Timeline during the f/8 conference in San Francisco in September. Paul Sakuma/AP hide caption

itoggle caption Paul Sakuma/AP