By Katie Marsal

Published: 12:25 PM EST

Apple has caught the ire of some developers this week after it was revealed that all applications with integrated Web browsers will reportedly be rated for ages 17 and up, and that all such apps will not be entitled to promotional codes.

As first reported at The Unofficial Apple Weblog, the App Store's new app rating system prevents developers from obtaining promotional codes for their applications. Such codes allow up to 50 free downloads for developers to distribute however they see fit, such as for publicity or promotion.

"As it stands, neither the 3.0 software nor iTunes display parental warnings when using a promo code to purchase apps with a mature (17+) rating," TUAW writes, "so Apple has made the promo code functionality unavailable for apps that fall into that category. We were informed of this condition by a developer who prefers to remain anonymous."

This has upset some developers, such as the creator of Instapaper and Tumblr, Marco Arment. The developer conveyed his frustration in a blog post Friday, saying he now doubts the viability of a business based on iPhone apps. Arment has expressed his displeasure with Apple before, specifically with regards to the iPhone maker's alleged unwillingness to answer developers' questions.

Now, Arment claims that Apple takes 8 to 30 days for review, and all Web-capable applications must come with nudity warnings.

"They’re making a killing taking their 30% commission on the 1.5 billion copies of $0.99 top-25 games that they’ve sold," he wrote. "Who cares if the App Store discourages good developers from putting serious effort into it? Apple doesn’t need to care. And, clearly, they don’t."

With iPhone OS 3.0, Apple added an age rating system for applications. This not only allows parents to set appropriate application access for their families, but also opens up the potential for developers to release applications with adult content.

Friday another developer also complained about the length of time in Apple's App Store approval process. Syncode, the developer behind the application iTweetReply, claims that Apple tested their application merely a few days after its submission to the App Store, but didn't provide a formal rejection until nearly a month later. The reason for the rejection: An illustration of an envelope displayed when the application launches included Apple's address, 1 Infinite Loop in Cupertino, Calif.

After the developer revised the application, it was approved two and a half weeks later.

"My personal guess is that once an app passes the initial technical test, it must be approved by multiple other levels from legal (to prevent illicit apps) to, well, God knows," Matthew Lesh of Syncode wrote. "If nothing else it has highlighted the need for a far more transparent approval process – Come on Apple, is it so hard to give us at least a quasi-detailed description of the approval process?"