However, according to Wikipedia, most people have a cell phone (67% of the world population). I would consider access to the cellular network equal to access to the Internet, since many services (such as Google's) are available to cell users. http://en.wikipedia.org/wiki/List_of_countries_by_number_of_...

Edit: And for what it's worth, I think you can operate your Facebook account fully through just a phone and text messages (but I could be wrong). No need for a full-blown computer and high speed internet.