Apple's 3rd Party iPhone Application Plan?
9to5mac suggests that Apple has already lined up specific development partners for 3rd party applications on the iPhone. EA is reportedly porting their existing iPod games over to the iPhone, with "other big developers" also on board.
9to5mac expects Apple to adopt an application model from T-Mobile's Sidekick, in which developers submit applications for review and approval.
If Tmobile/Danger feel the application is stable, won't interfere with other applications and would be of interest to their customers, they make it available for download and install through an integrated payment system. The cost of application is added to the customer's monthly bill. The Danger team actively works with the developers to insure compatibility and stability in applications through SidekickOS updates.
The site also suggests that Apple will continue to thwart efforts for user-installation of 3rd party apps to reduce piracy concerns.