The day many iPhone developers have been waiting for has arrived. Yes, I’m talking about the availability of adult content on the iPhone.

Thanks to the iPhone 3.0 OS, which includes parental controls, the App Store has its first officially sanctioned app that provides adult content.

The app with the distinction goes by the somewhat unoriginal name Hottest Girls and depending on which way your moral compass points, it’s either the beginning of a great era in the App Store or the beginning of The End.

Prior to the release of the iPhone 3.0 OS, Hottest Girls displayed photos of scantily-clad women. Post-iPhone 3.0 release, it now comes with fewer articles of clothing. The app’s listing in the App Store notes that “You must be at least 17 years old to download this game“.

Unless some mistake has been made, expect a flood of similar apps and a new App Store gold rush. But beware: all that glitters is not gold. Apple has a very fine line to walk. The mere presence of a parental controls system isn’t going to prevent criticism from being leveled at Apple.

The question for Apple is how far it’s willing to go. Adult content on the iPhone would almost certainly be a significant profit center but if Apple goes too far and the App Store becomes seen as the virtual equivalent of a filth peddler, all bets are off.