Apple’s Steve Jobs announced today on the company’s Web site that he wants native third-party applications for the iPhone and will have a software development kit for developers by February 2008, that will have some kind of advanced technique for ensuring that only safe programs end up on the iPhone.

But there were few details in Jobs’ blog post. Those details will determine how those native applications are developed and just as importantly how they get distributed to iPhones in the field and who collects the revenues.

“We are excited about creating a vibrant third-party developer community around the iPhone and enabling hundreds of new applications for our users,” Jobs wrote. “With our revolutionary multi-touch interface, powerful hardware and advanced software architecture, we believe we have created the best mobile platform ever for developers.”

Jobs writes that Apple has two potentially conflicting objectives: making it easy for iPhone developers to build and distribute applications and making it difficult for those applications to break the iPhone or introduce malware. Balancing them is “no easy task,” he writes.

“There have been serious viruses on other mobile phones already, including some that silently spread from phone to phone over the cell network,” Jobs writes. “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.”

This appears to mean that there will be developer and user constraints. Jobs noted that Nokia now blocks applications downloading on its phones unless the software carries a digital signature from a bona fide developer. “While this makes such a phone less than “totally open,” we believe it is a step in the right direction,” he writes. “We are working on an advanced system which will offer developers broad access to natively program the iPhone’s amazing software platform while at the same time protecting users from malicious programs.”

Long-time Mac developer Christopher Allen, founder and facilitator of the iPhoneWebDev.com site, says it’s unclear as yet what Apple’s plan actually is. Rather than true native applications, what Apple may have in mind is something closer to the widgets in Mac OS X and the upcoming Leopard operating system. “It can look beautiful, have a great [user interface], but most it is JavaScript and XML, and some native function calls and snippets of highly efficient C code,” Allen says.