I've only told two of my closest friends, they each had very different reactions:
1) When I told my closest male friend, he said he suspected I had it, and now whenever I use my Aspie memory/intelligence to my advantage he jokingly calls me out on it, as if I'm cheating in the game of life. We can make jokes about it and neither of us cares. This is, in my opinion, the ideal reaction. I'd like to be able to joke about AS with people, it makes it much easier than pretending it doesn't exist.
2) Since I told my closest female friend, she's sort of taken on a nurturing motherly role with me, for which I'm very grateful. For instance, she'll help me through tough social situations, give me social advice when I ask, and try to get me to be more social by inviting me to social gatherings of her group of friends. Unfortunately she overdoes the motherly thing sometimes, to the point where it can backfire on me. For instance, after socializing with her group of friends a couple of times I realized that I was attracted to one of her friends- we'll call her Gabrielle. Apparently I'm not Gabrielle's type, and I was willing to accept that and move on (Hard as it may be). My friend, however, wasn't, because it was the first time she'd seen me attracted to anyone, and tried repeatedly to "set us up", which, I suspect, may have made Gabrielle indirectly irritated with me.
I think these are both the best reactions I could have gotten, even if it's a bit overdone in the second example. A best same-sex friend you can be open with and don't have to hide your ASD from, and a best opposite-sex friend who will be willing to metaphorically hold your hand and be that nurturing, even slightly protective, big sibling type of person. It's a bit ironic in my case because I'm actually older than her by about a year.