The word is Apple has sent out email invites to select members of the press for an early showing of the new upcoming iPhone operating system, iPhone OS 4.0, all of those who have received the invite are in the United States.

According to itproportal, it is fairly likely that Apple will release a new iPhone SDK for the iPhone OS, and apparently quoting an article over on engadget there are to be 3 distinctive forks aimed at the iPhone, iPod Touch and iPad.

There have been numerous rumours over iPhone OS 4.0 which range from the addition of full multitasking on the iPhone to a video calling feature, and that the iPhone OS 4.0 will use the Expose user interface which can be found on their desktop computers.

Speculation over the appearance next generation iPhone which is currently being referred to as the iPhone 4G or iPhone 2010, or iPhone HD and such still continues with the guys saying they expect it to be unveiled during the Worldwide Developer Conference in San Francisco at the end of June.