Today, according to reports from both TechCrunch and 500px's Twitter feed, the app has returned to the store.
The app returns with an age-gate warning, advising that the content in the app is for 17+ audiences, and also adds a new “Report Photo” button to help users quickly tag things they find offensive for potential removal from the network.The return of the app follows the removal of Twitter's Vine as an 'Editor's Pick' on the App Store after a pornography scandal on that platform.
The app still has a category for “Nude” photos for logged in users, however, which is an impressive allowance on Apple’s part
500px is a free download on the App Store. [Direct Link]