Nielsen Online, an analytics firm that tracks time spent online at various websites, has issued a report finding that throughout 2008 social networking sites and blogs saw more time spent by users than personal email. While not shocking, the finding does mark an important point in the history of the web.

Youth watchers have long argued that for young people, email is how you communicate with elders in formal situations, while social networks and SMS are the preferred method of communication among peers. Nielsen found, however, that Facebook in particular saw greater growth among older people than it did among the young.

This shift has primarily been driven by Facebook, whose greatest growth has come from people aged 35-49 years (+24.1 million). From December 2007 through December 2008, Facebook added almost twice as many 50-64 year old visitors (+13.6 million) than it had under-18 year old visitors (+7.3 million).

Our take away from these findings? People prefer the clean, controlled, multimedia and publicly social experience of social networking communication over the relatively open, individualistic and spammy medium of email. The fact that there is effectively no data portability allowing communication archives to be ported from one social network to another as there is with email doesn't appear to be bothering people in the short term. We wonder if it will in the long term.

For a more in-depth look at this phenomenon, check out Danah Boyd's latest analysis titled "Social Media is Here to Stay - Now What?."