Oh man yes. I think I got email in like grade 5, and I wince when I even think about my ten-line email "signature" or all the forwards I forwarded. If I'd had facebook then, too...? Urghhhhhhhhhugh.
As it stands, I try to keep my facebook profile really really private and not filled with super-personal content. I've seen enough Semi-Serious Shit Go Down that I'm extra paranoid about photos and who I'm friends with and etc. I'll probably still screw up majorly at some point, though.