If I learn about your big life update via facebook we're not really friends, are we?
I wondered about this from the very start. My slow adoption of facebook (and once monthly logins) reflect my thoughts on what it does for friendship. I think it really helps you to get lots more information on your acquaintances and former friends. (Possibly it also helps with event planning?) But as for bringing me closer to my actual friends, no, it has not strengthened any of those ties.
There are friends and there are facebook friends... sometimes those even overlap!