Have you tried using his obsessions to help him make friends? Wrongplanet.net was created by an Aspie and there are a bunch of kids that talk about programming. You could also see if there is a programming summer camp where he could find kids that have the same interest, if you can't find a good camp try checking your church or library and maybe he could start one if there is not one in place. Now on regards to his friend I think you are going to have to remind him every other day in a friendly tone that not everyone has the same likes, and just like he wouldn't like to be talking about girlie things like nail polish every day his friend may need a break from the topic, I would recommend you use different examples on your sons dislikes and the friends likes so he can create a bigger picture of what's going on.

He has joined clubs that interest him, he was in robotics club and he has just started playing chess, which the girl I was talking about expressed an interest to be taught by him...so we are making progress ...yay!!!

Awesome!

the more attention that behavior is given the worse it will get.

He actually has this computer program he created that he had a couple of kids(that I have come over because he has a hard time making friends and he encouraged them to join it, he puts assignments on there....one is a particular girl who has autism not sure where on the spectrum it is... but she does not want to do the program anymore and he continues to talk to her about it, text her about it and it's stressing her out. I do not want him to put this friendship in jeopardy because they understand each other but he just won't let it go