With 500 million members, Facebook is bound to have some users beyond the 20-something crowd. In fact, activity on social networks for those over 50 has nearly doubled in the last year, according to a Friday study from the Pew Internet & American Life Project. PC magazine reports:

In April 2009, about 22 percent of those over 50 had tried a site like Facebook or MySpace. That has jumped to 42 percent in May 2010, Pew said. Among those ages 50 to 64, usage during the same time period grew 88 percent, from 25 percent to 47 percent. The over 65 crowd, meanwhile, grew 100 percent, from 13 percent to 26 percent.

For comparison, social-networking use among users ages 18 to 29 grew by 13 percent, from 76 percent to 86 percent.

"Young adults continue to be the heaviest users of social media, but their growth pales in comparison with recent gains made by older users," Mary Madden, senior research specialist and report author, said in a statement. "E-mail is still the primary way that older users maintain contact with friends, families and colleagues, but many older users now rely on social network platforms to help manage their daily communications."

Results were based on phone interviews with 2,252 adults, Pew said.

Older users who access social-networking sites on a daily basis – about one in five – is up 10 percent from last year, Pew found. About 13 percent of those ages 65 and older do the same, up from 4 percent last year.

Internet in micro-blogging site Twitter has also grown, according to Pew. One in 10 Internet users over the age of 50 now use Twitter to share updates about themselves or get updates about other users.