Once thought to be building Flash for the iPhone mostly on its own, Adobe has mentioned at the World Economic Forum that it's not only continuing work on the animation plug-in but has teamed up with Apple to make it a reality.

In an interview with Bloomberg at the Davos, Switzerland event, Adobe chief Shantanu Narayen describes development as a complicated two-way process rather than maintaining the previous image of a one-sided effort that would depend on App Store approval before it could launch.

"Itâs a hard technical challenge, and thatâs part of the reason Apple and Adobe are collaborating," he says. "The ball is in our court. The onus is on us to deliver."

What hurdles Adobe has to overcome aren't mentioned by the executive, though the company's long porting process has underscored the difficulty involved. Narayen had said that he was "pleased with progress" as far back as June of last year — just three months after the iPhone SDK made native third-party apps an option on the touchscreen device.

Apple co-founder Steve Jobs has maintained since nearly a year ago that the real obstacle is the nature of Flash itself. While desktop Flash is too resource-heavy for the small processor and low memory of smartphones like the iPhone, Jobs has warned that Flash Lite is too feature-limited and doesn't do many of the things users expect Flash to do — such as playing video on the web or showing complex animations on websites.

Most Flash Lite implementations actually depend on an app that runs entirely outside of the web browser and are often based on older versions of Flash that limit their performance and feature set; Jobs has argued for a "product in the middle" that does more.

Whether or not the collaborative process involves working on that app is very much a mystery, but it may be necessary for Flash to appear in Apple's preferred form, as third-party iPhone apps aren't allowed to serve as plugins based on the iPhone SDK's guidelines.