The Apple rumour machine kicked up steam this weekend, with an initial batch of reports warning the company may institute a 'walled garden' approach when it introduces the iPhone software development kit.

Some reports warn the final version of the iPhone SDK may not ship until later this year, potentially when the company hosts its Worldwide Developers Conference in June.

iLounge claims iTunes will act as a hub from which customers can purchase third-party applications, this also means Apple will be able to vet which applications are permitted to legitimately ship.

However, subsequent reports from other sources suggest that while Apple will vet iPhone/iPod touch applications sold through iTunes, it will be more liberal in approach when it comes to free software applications, offering little scrutiny on these in an attempt to promote development of bespoke business and hybrid software and service applications.

The iLounge report also suggests Apple won't permit developers full access to all the features of the device, explaining that solutions marrying hardware with software - such as voice recorders or GPS modules - won't be permitted, at least not in this particular model.

Integrated iPhone or iPod touch features such as the phone, WiFi, and camera will be developer-accessible, though the iPhone's artificially limited implementation of Bluetooth 2.0 may not.

The report indicates that Apple will introduce a beta version of the iPhone SDK at this week's event.