So "faggot", which means "you should burn", has evolved to mean "male homosexual"? Wow, that's kind of scary...
I would argue that calling someone "gay" is a form of bashing. I don't mean to be disrespectful to homosexuals, but challenging someone's sexuality is a severe insult (at least, in the society I live in).
Though ironically, there's a big difference between using it passively and using it seriously. Sometimes, if I playfully diss a friend of mine, he might laugh along and make his comeback by calling me "gay". He had a reason for it and doesn't really mean it at all to begin with - that's fine. But if someone randomly called me gay for absolutely no discernible reason at all, I'd make a mental note of that person
Having said that, I am against the use of that particular word as an insult, which is why I avoid it myself (my variation is "screw you", something I also tend to avoid typing because it looks a lot more confrontational in writing than it sounds when I say it
). However, I think that, with so many people using it as an insult these days, the only way it'll ever stop is if it is naturally phased out over time.