It definitely is, but (in the worst case) there is always peer pressure or third parties romanticizing/confusing your friendship with something else until you're convinced (and regret that later).
I agree. I'm a 19 year old female and I find that people my age push sexual, if not emotional, pressure on any relationship between a man and a woman. But when it's been made clear by both parties that they don't see each other that way, or if no third parties become involved, it's definitely possible to have an honest friendship. (And talk about romance, video games, politics- anything. And it's perfectly non-sexual/romantic.)
"...or if no third parties become involved." Well said. Even if it is just a friendship between a man and woman (in my opinion a way less "threatening" situation), other people shouldn't act on their need to interfere based on gender (or species). Actually, I wonder how much the dynamics of such a combination would differ compared to same-sex friendships, since the goal (assuming friendships are founded on shared interests and goals) might be different (arguably more interesting as well).
To counter the main question: I wonder if true friendship between two men or two women is possible. I suppose it is, but I've seen more/worse forms of betrayal in such a combination than between a man and a woman.