New iPod peripherals from Belkin may just be the beginning, as Apple has opened up certain hitherto hidden features so developers can create add-ons to extend its versatility.

Insider reports in the prelude to last week's iTunes Music Store launch had confirmed a partial opening up of features to certain developers. These reports have been confirmed by Cnet, which notes Apple to have been surreptitiously working with third party peripherals vendors to increase the number of available add-ons for iPods.

Apple senior VP of worldwide product marketing, Phil Schiller, told Cnet: "There's things that we've done to help other people bring the iPod into other markets and other uses."

Observers have already noted that the new model iPods carry more control 'pins' within the FireWire port than required for the product's existing functions – presumably a forward-thinking move that laid the ground for Apple's current plans. Hidden software features were also unlocked last week to allow Belkin's introduction of a voice memo recorder and flash-memory-card-reader product.

Cnet adds that Apple has posted instructions for developers that let them exploit the device in a "museum mode" – a customized interface that lets the product be used as part of an audio tour. The company is also canvassing for ideas as to how to extend the product's capabilities.

Apple is understood to be acting selectively in the third party companies it chooses to work with.