Joe. My. God and it got me thinking about a few things, like for starters how much cooler than the US Canada must be if they put this up in the first place. Aside from that, it makes me think about representations of gay people in main stream advertising. I would suspect that this is targeted to bus shelters in neighborhoods with high gay populations, but obviously plenty of straight folks will see it as well.
To my estimation, in a society where it is acceptable to show a man and a woman kissing on a billboard, it must be acceptable (at the minimum) to show two people of any sex and gender presentation doing the same. However, this isn't an affront just to hard line right wingers but to lots of people who say things like "it's fine what people do in the own bedrooms, I just don't need to hear about it." For just right now I'll sidestep my issues with the weird, Puritanical notions we have about most or all sex and sexuality in our culture, and address the issue specifically at hand.
Coming out about our sexual orientation but leaving all of our epressions of sexuality and even affection behind in the closet plays into the idea that there is something pathological and deviant about sexual expression outside the hetero norm. It is important to have positive images of same sex and other gender non-conformist sexuality become so regular in society that I can walk down the street every day for a week holding hands with a man, kiss him goodbye when I get on my bus, and never be taunted or, worse, threatened or attacked. Of course this ad represnts the beginning - two fit, masculine, white men sharing a kiss. We're a long way from a black bull dyke dominatrix sharing a kiss with her collared femme, but a Radical Faerie can dream, can't she? ;D