Previously the company had taken a closed platform stance for the gadgets, denying access to any third party programs without unofficial software modifications. A software update last month caused many unlocked iPhones to cease to function, closing any doors to the idea of running non-Apple code on the devices.
Although not alluding to the reasons for the company's about-turn, Jobs wrote: "Let me just say it: We want native third party applications on the iPhone, and we plan to have an SDK in developers' hands in February.
We are excited about creating a vibrant third party developer community around the iPhone and enabling hundreds of new applications for our users.
"It will take until February to release an SDK because we're trying to do two diametrically opposed things at once — provide an advanced and open platform to developers while at the same time protect iPhone users from viruses, malware, privacy attacks, etc. As our phones become more powerful, these malicious programs will become more dangerous, and since the iPhone is the most advanced phone ever, it will be a highly visible target," added Jobs.
"We think a few months of patience now will be rewarded by many years of great third party applications running on safe and reliable iPhones."