Definitely have some time apart before you try to be friends. A friend of mine broke up with his girlfriend recently, and his attempts to be friends with her immediately led her to believe they were basically unofficially getting back together, which led to a massive blow up when she found out that wasn't the case. They don't talk at all anymore.
I haven't spoken to my ex at all since we broke up (about a month ago). We acknowledged, even at the time, that we'd have to be friends, though, or at least on good terms, since we're doing a whole year of study together this year in very small classes. I still have all his books, though, and I don't know how to give them back. I considered just passing them over on the first day of class, but I don't want to make a scene. I also don't really want to meet up with him just yet to do it that way :\