It's SO funny that this thread should pop up!
I have a friend whom I hadn't seen since Freshman year of high school. We were very close all through grade school, but lost touch afterwards.
She showed up to my dad's funeral a few weeks ago!
She said that she had been trying to find me so that we could catch up. She happened to see my dad's obituary, and showed up!
This was extremely touching to me, because I have people with whom I've been friends for over 10 years who didn't even show up to the funeral. But she came, we talked for hours afterwards, and decided that we will keep in touch. After the catching up was done, it was like we never lost touch! It's pretty amazing!
ETA: I have a theory on this by the way...The friends we had when we were kids were just that. Friends. No strings attatched, just friends. Too often when we're adults, we let silly things (like money and who owes a favor to whom) get in the way of true, unadultered friendship. It's like kids just have this ability to be "pure friends". Kids are simply drawn to the other kids with whom they have something in common. I think that's why these friendships can usually stand the tests of time and distance.

It's when we grow up and learn the "politics" of friendship that we lose sight of that...