That translates into about 14 million people who were using the 'read-write Web' to contribute to political discussion and activity," the study's authors Lee Rainie and John Horrigan write.
Pew's findings again suggest that the much-feared "Daily Me" balkanization and creation of self-reinforcing echo-chambers doesn't appear to really be a problem. Folks online are probably exposed to as much, or more, information that challenges their point of view as anyone else.
This is a good run down of the results from the Pew study.