Old_Honky - 1:24 pm on Dec 27, 2009 (gmt 0)

I very much doubt that the figure of 20% has any basis in reality except amongst facebook users.

Even in the USA the proportion of married couples who use facebook is far less than 20% before you start. Facebook, twitter et al are only relevant to the small minority of people who use them. The vast majority of people have better things to do with their lives than communicate with pseudo friends whom they have never met, are never likely to meet, and when it comes down to it they don't really give a toss about.