Just a few short years ago, Facebook was the exclusive province of postmillennial college undergraduates. Well, move over. The Woodstock generation -- and their parents -- are moving in.

The phenomenal growth of Facebook, Twitter and other social sites in the past year has come in part because of a surge in adoption by older members, with a national poll released Friday providing a surprising new measure for how fast baby boomers and seniors are adopting online social networks to bridge generations and geography.

The survey by the Pew Research Center's Internet & American Life Project shows that the share of Americans older than 50 using social networks doubled in the past year, with a virtual majority of baby boomers, and about one-quarter of the nation's seniors, now using the sites to stay in touch or reconnect with long-lost friends.

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