California may be far away geographically, but there’s an issue right there that hits home for every web marketer. It’s really quite simple: Californians are going to vote soon on “proposition 19,” a resolution to de-criminalize marijuana for personal use. Note, we’re not talking about medical marijuana any more, we’re talking about lifting prohibition altogether.

Who cares? Well, apparently some major websites do. And the way they care is by refusing to run ads supporting Proposition 19. Yes, you heard that right. Not for any amount of money!

Facebook, for starters. They recently forbade even displaying an image of a marijuana leaf in an ad. And it’s quite ironic that we have to link to Wired to report this story, because Wired belongs to Conde-Nast Media, which also owns… And guess who else won’t run a pro-Prop-19 ad?

The Reddit reaction is amusing. Reddit users responded to the ad ban by submitting story after story about Prop-19 – with marijuana leaves festooned – until the entire front page consists of nothing but support for Prop 19. We haven’t seen a social-news-site rebellion like this since the great HD-DVD encryption key code backlash of 2007.

Well, anyway, file this under “know your market.” The web audience is a feisty little critter some days, isn’t it?