Anecdotal examples: Brazilians upload lots of pics, have tons of orkut/facebook friends, "chain-like" updates ("blablah, if you agree with this post it on your wall"). are not uncommon, etc. Meanwhile, many of my Japanese facebook-friends don't even have a real pic of themselves as their profile pic, they usually don't add coworkers, etc. Americans might be somewhere in between.

You could probably find data that quantifies those anecdotes. If you want to talk more about it feel free to send me a message (my email address is in my profile).