22 percent of registered voters have announced their vote already on a social networking site, a new Pew survey says. Nearly a third of people between the ages of 18 and 39 have done so.

These messages are interesting because they don't come from campaigns or their surrogates. Twenty percent of registered voters have used social networks to encourage friends and family to vote, with about even numbers promoting Obama as Romney, reports Pew.

Slightly more Obama than Romney supporters have announced their votes on social networks (25 percent:20 percent), but Pew says the "difference is not statistically significant."

These findings are based on phone interviews from Nov. 1-4 so they reflect the experiences of early voters.