Drinking beer from a can IS tacky. Mainly, because BEER THAT COMES IN A CAN TASTES LIKE SHIT. Winnie's right, it depends where you are. I don't think you should feel like you have to order wine or a mixed drink if what you really want is beer, though - that just wastes money, either yours or whoever's buying it for you.
Just as a note to the sorority girls who must poor their beer into a glass: it makes it a heck of a lot easier for someone to slip a roofie or something else into it, not to mention one of my friends got hepatitis once from drinking out a glass at a bar (if she'd left it in the bottle she'd have been fine). So good luck with that.