oh yes, I've definitely changed my views on several topics. Some issues are not really that essential to a friendship (like becoming anti-death penalty). I'm not nearly the hawk I used to be in my younger years, but I usually avoid political disucssions if I can.
But, I did completely change my Christian tradition away from Protestantism. That's a little hard. Some friends really don't care, but others do. It's an important part of who they are as it is mine, and we're so different, that it's hard to overcome. Most of them I wasn't real close to anyway, and a couple of friends moved away right around the time I moved away theologically from Protesantism. But, I did make new friends within my tradition. I also don't need a ton of friends, but I do like to have a diverse group of them. I think it keeps me thinking about what I believe and also helps me to be respectful of their beliefs too. But, of course, not everyone thinks that way.