Some specific data on this, as well as related information about how people in (or looking for) relationships interact in the digital age can be found in the results of the latest Zagat Dating and Dumping survey. This press release about it says that "52% of surveyors confessed to 'Googling' a prospective date, and 41% said they used Facebook to snoop around their date's information and check out photos".
So, it's obviously a good idea to Google yourself from time to time. The nature of your online presence clearly has ramifications for both your career prospects and your love life.