Six Four degrees of separation
I just read an article on Mashable, which goes back to our lecture about network theory, Barabási, Milgram and the others.
Apparently an Italian university wrote a study with the help of Facebook itself, and they found that - in our Facebook dominated age - for 92% the average distance between people went down to about 4 instead of the 6 mentioned before, for another 7,6% it's 5 degrees. And it keeps getting smaller and smaller, year by year.
You can read a bit more here, it's not a long article.