Gizmodo and Engadget have reported the discovery of a 3G on/off switch in the iPhone’s latest firmware upgrade. Also discovered was a warning that using 3G would kill your battery life quicker. The question now is not if the iPhone will be 3G, but when the 3G iPhone will be released.

A quick check of the US and UK online Apple stores shows that both versions of the iPhone are now currently out of stock. Popular predictions were that Steve Jobs would announce the 3G iPhone on June 9 at the World Wide Developer’s Conference, but surely it’s not a financially sensible plan for the Cupertino based company to halt iPhone sales an entire month before that date. While there is the possibility they have miscalculated stock numbers and now don’t want to refresh stock with only a month to go before 3G, it’s highly unlikely. Both 8GB and 16GB iPhones are out of stock at exactly the same time in both the UK and the US.

There is one other possibility. Jobs is about to pull a blinder. The surprise is not that the next generation iPhone is 3G, it’s that it will be released ahead of schedule.

Do you think the iPhone will come early? Tell us in the forums.

[Picture from Engadget]