It's actually pretty surprising that it took everyone three days to figure out that Twitter's new cell phone camera-powered video sharing app, Vine, is perfect for porn. Vine has it all. It can record reasonably high quality videos of anything you want, on-the-go, and post it publicly for all the Internet to see. You add hashtags so that people can easily find special interest content. There's even a little comments section so that you can share your thoughts about the distinctively addictive six-second loops. Heck, we'd be surprised if people didn't immediately start to post pictures of their genitals doing what genitals do. They probably did, actually. Everyone else was just too busy watching pictures of their friends pets and children to notice.

But alas, by Sunday everyone had noticed. Although it had already been mentioned on smaller tech blogs, the Vine porn problem started to become widely known after New York Times reporter Nick Bilton tweeted, "Friend: 'So are people using Vine for porn yet?' Me: "'Nah, I don't think so.' Friend: 'Check the hashtag #porn." Both: "Holy ****!'" And the thing is, he's totally right. TechCrunch published a post on the NSFW trick -- #NSFW works for porn seekers, too, by the way -- broaching the topic of Apple's App Store coming down hard on the adult-only content. It's against the rules, see, and Apple has a history of yanking apps that become magnets for all things naughty. The Verge followed up a few minutes later with the headline, "Apple has a porn problem, and it's about the get worse."

This got us thinking: These App Store restrictions on pornographic content have been around as long as the App Store. Surely in the past five or so years, the moderators know a porn magnet when they see one. Vine is hardly the first video-sharing app to make it through the approval process, not to mention the many photo-sharing apps. (And Apple's certainly not afraid of enforcing those rules, as we learned when it yanked the 500px app after it started to become home to "pornographic images and material.") It's no anomaly that Vine made through, though. As virtually every new video- or photo-sharing service has shown us since the dawn of the Internet, from Flickr to ChatRoulette, it's very difficult to keep these sites or apps G-rated. So the companies either learn how to police it well, like Flickr does, or they wither and die, as ChatRoulette did.

It's hard to believe that the App Store didn't consider the fact that people might upload pictures of their penises to Vine. It's more likely that they did and decided to see how Twitter would deal with it, when it became a problem. After all, Vine is not going to be the last video-sharing app to be built and it certainly won't be the last porn-friendly app to be built either. So Twitter gets to play guinea pig and navigate the tricky terrain of moderating user-generated content in real time. It's a good thing they already have a boatload of experience doing that on Twitter! See, look how fast they came up with a solution. A company statement reads:

Users can report videos as inappropriate within the product if they believe the content to be sensitive or inappropriate (e.g. nudity, violence, or medical procedures). Videos that have been reported as inappropriate have a warning message that a viewer must click through before viewing the video.

Uploaded videos that are reported and determined to violate our guidelines will be removed from the site, and the user that posted the video may be terminated.

Twitter being Twitter -- that is, big proponents of the free flow of information -- they stop short of defining "inappropriate" in Vine's terms and conditions. Unlike Twitter, which has been free to operate on the whole of the Internet, however, Vine lives in Apple's house now. If Twitter's hands off policy doesn't do enough to keep smut off the iPhone, Apple will surely pull the plug, and then, well -- then we'll be back to where we were last week.