Apple's confirmed that a series of iOS 5 bugs are causing battery problems for many iPhone 4Ss.
It's told AllThingsD that it plans to release a software update to users that should address the problem in a few weeks' time.
In the meantime, it's released the new beta version of iOS 5.0.1 to developers. The new version is reported to fix the battery issues, as well as reinstating multitasking gestures for the original iPad, improving security and fixing bugs relating to documents in the cloud.
However, according to AppleInsider, many developers are having trouble activating their devices with the new versions of the OS and are advising others to avoid it.
Many users have complained on the company's support forum that their battery is lasting 12 hours or less, and there are plenty of theories as to why.
Some users have found an improvement by turning off the Setting Time Zone feature, whereas others suggest that Diagnostics & Settings is causing the battery drain by sending large numbers of messages to Apple.
The Apple statement implies that there's more than one cause.
Apple has something of a history with problems in early versions of its phones; last year, the iPhone 4 was found to have a faulty antenna design which took weeks to sort out.
Its track record doesn't seem to have put users off, however, with iPhone 4S sales topping four million in the device's first weekend on sale.