Apple recently updated its OS 3.0 iPhone software to include parental controls that restrict some applications to people over a certain age. (Canadian Press)

The first app featuring images of nude women to go up for sale on iTunes can no longer be downloaded because it was too popular, the developer reported Thursday.

"The Hottest Girls app is temporarily sold out," said a post signed by the "ATG dev team" on the website of developer Allen Leung.

They added that the servers distributing the app were crashing due to high usage. However, they noted that those who have already downloaded the app will be able to use it, and assured customers that "the topless images will still be there when it is sold again."

"Hottest Girls," which billed itself on the developer's website as the "first and only app with nudity," was updated Wednesday to include "completely naked pics," according to the description at the iTunes store. It is available for download to customers 17 or older to run on the iPhone and the iPod touch.

Previously, Apple would not approve that kind of material for sale on iTunes.

However, Apple updated its OS 3.0 iPhone software this month to include parental controls that restrict some applications to people over a certain age. That led to widespread speculation online at sites such as MacRumors.com that the door would soon be open to porn.

The "Hottest Girls" application for the iPhone and iPod touch costs $1.99 and boasts more than 2,000 photos of "hand-picked images of the finest looking girls" that are automatically updated. A previous version of the app, released in May, contained scantily clad women, but none who were naked.

At least one online review, however, said even the new, nude images are relatively tame.

Wired News columnist Charlie Sorrel called them "distinctly softcore."

"While there are nipples to be seen, that's about it," he wrote on the magazine's Gadget Lab website. "A smartly worded Google image search would do better if you're looking for titillation."

Confusion for developers?

Nigel Wallis, director of software and services for IDC Canada, a research company that analyzes the technology industry, said Apple's decision to allow explicit apps on iTunes means it has a lot of faith in its new parental controls.

"Apple cares a lot about their brand," he added. "It's an exceedingly large part of the company's worth."

Presumably, he said, the company thinks adult-oriented apps could be a huge potential market and a source of large revenues.

Wallis noted that Apple has banned a number of other applications in recent months that could potentially tarnish its image, such as one from the band Nine Inch Nails and another featuring the South Park cartoon. In April, the company also pulled the plug on the "Baby Shaker" application, which prompted numerous complaints. The app let users shut off the sound of a crying baby with a vigorous shake.

Given its recent track record, the decision to allow adult apps may confuse developers, Wallis said.

"It would be nice to have a bit more clarification from Apple in terms of what's in, what's out."