Since the device's announcement at Macworld '07 earlier this year, one of the largest questions everyone had for Apple was whether the company would allow 3rd parties to develop applications for it. After all, with such a powerful device and what is likely to be a very, very broad user base, not allowing users extend the functionality of the iPhone could be a significant - if not mortal - roadblock for the device. At one point, Apple VPs confirmed there would be no 3rd party apps, and even Steve Jobs himself confirmed that the iPhone would be a closed platform in the name of security and making sure users didn't take down the West Coast AT&T network because "some application messed up." As you can imagine, this comment was widely slammed, largely because plenty of other mobile phone platforms (Windows Mobile, Symbian, Palm, etc.) allow for 3rd party apps, and to this day no phone has reportedly knocked out any portion of a coastal network.
Still, users and developers saw through this bizarre smoke screen and still requested a more relevant and definitive answer as to whether the iPhone will allow 3rd party apps. Eventually, Jobs began to hint at the possibility, telling the community that Apple was 'considering the possibility.' Today, finally, Steve Jobs revealed Apple's plan for allowing 3rd party apps on the iPhone, and it surprisingly involves Safari and web 2.0/AJAX technologies.
Both on stage during today's WWDC keynote and in a press release issued this afternoon, it was revealed that the iPhone will allows 3rd party apps which:
look and behave just like the applications built into iPhone, and which can seamlessly access iPhone's services, including making a phone call, sending an email and displaying a location in Google Maps. Third-party applications created using Web 2.0 standards can extend iPhone's capabilities without compromising its reliability or security.
This is an interesting compromise for Apple, and one that has understandably been met with mixed fanfare. On the one hand, leveraging web technologies will allow both Mac OS X developers and web developers to easily get their apps onto the iPhone. This opens the door for a lot more people to get their apps and services on the iPhone since they won't have to learn the entirety of Mac OS X. Interestingly, this could have a serious effect on Safari's market share (or WebKit's share, depending on how you look at it), since Apple has now made their browser available for Windows and a hotly anticipated mobile device.
On the other hand, developers might understandably feel a bit constrained by the limitations of web technologies and not having full access to the iPhone's operating system like they do on a real Mac running Mac OS X. While Steve Jobs demonstrated some surprisingly powerful apps built to run in Safari on the iPhone, this doesn't mean every desktop app that users want a mobile counterpart for can sufficiently run in an environment that's limited by web 2.0 and AJAX.
Of course, it's still very early to tell; while the initial reaction to the iPhone 3rd party app compromise has been mixed, we'll all just have to wait and see what the 3rd parties can make of this system when the iPhone is released and the apps start (hopefully) rolling in.