A soft-porn iPhone and iPod app that showed a selection of naughty, but not naked, females briefly made an appearance on the Apple App Store at the weekend.

Wallpaper Universe from FunMobility, a maker of Apple Apps, ringtones and wallpapers, debuted on the Apple App Store on Friday before mysteriously disappearing on Saturday.

Apple famously doesn’t do porn, although there's no mistaking what the app is about. Even so, few people would have found the pictures on display offensive, with underwear covering the women’s modesty in the photos we saw.

Apple won't reveal what goes on behind the scenes with their approval process, a process that often takes weeks, although someone at Apple appears to have clicked ‘approve,’ perhaps a little over excited, before checking the App's full credentials.

There is a more serious side to this, Apple recently approved an app called BdEmailer, which duplicates Apple's Mail app (in contradiction to another contentious rule). This prompted Joshua Topolsky from Engadget to say: "either you've relaxed your policies on duplicate functionality, or you've gotten incredibly lazy when it comes to approving applications. We're inclined to believe it's the latter, as BdEmailer has a fair share of bugs that need working out, but really, people need some clarification here on what will and won't pass -- and moving the goalpost all the time isn't going to help."

Apple rejected Internet Radio application CastCatcher entry into the App Store because of bandwidth concerns earlier this month, despite three prior releases to the store being accepted by Apple.

And, of course, if an application as obviously unsuitable as Wallpaper Universe can pass through Apple's approval process, what's stopping a more seriously malicious program from being approved?

Image via VentureBeat.

Get four free Mac programs worth £82 and 40 free prints from Jessops with Macworld print magazine. On sale now! Click here for more information.