One of the underground developers working on hacking iPhones says that the Apple SDK is "crippled," and predicted that the thriving market in jailbroken applications will continue.

The iPhone Atlas quotes Jonathan "NerveGas" Zdziarski, who recently released the book "iPhone Open Application Development" through O'Reilly Publishing:

"The Apple SDK, as many have come to find, has arguably crippled much of the functionality that set the iPhone apart when first released. Even simple features like the ability to run a program in the background have been crippled in the Apple SDK."

Signed applications that run under Apple's scheme lack the ability to run in the background, as many of Apple's own applications -- including the Mail program and Clock -- do. Unofficial applications created under the jailbreak umbrella carry no such restrictions. Apple's motives for limiting this functionality aren't clear, but some have cited stability concerns.

He predicted Apple will sign sweetheart deals with software vendors to go beyond the limitations of the SDK.

Previously on InformationWeek.com

Will The SDK Be The iPhone's Achilles' Heel?

iPhone SDK Developers Angry At Apple's Tight Control