In any case, the latest survey from Strategy Analytics showed that battery life is what users are most unhappy about with their iPhones. Well, unhappy might be too strong a word.
Honestly, I'm not sure how much things will improve with OS updates and future hardware upgrades. We aren't exactly seeing a breakthrough in battery technology. Plus, if you haven't noticed, we are in the beginning stages of a mobile hardware war - speed and 3D acceleration for gaming and other mobile features. It isn't as simple as the old Mhz war between Intel, AMD, and PowerPC but it'll be about cores and graphic accelerations.
As a result, battery life will be continued to be impacted greatly. Plus, Apple will never produce and iPhone with a user-replaceable battery. As highlighted in the report, iPhone warriors are increasingly relying on their iPhones for their link to the Internet, mail, and other wireless communications.
It's time the iPhone, despite having the "phone" in its name, is a mobile device with a very powerful mobile platform as its backbone. Fortunately for us, I think Apple see this as well and claiming the iPhone as more of a mobile computer than a smartphone is more than just marketing.
I think if Apple can even squeeze out another 20-25% more battery life would make everyone happy. Word is that Apple is very meticulous about picking the right chips for the iPhone and the iPod Touch and is even going as far as to buying a chip design company to make its own mobile chips.
Perhaps, with the right chip and the battery technology we see being used in the Macbook Pro lines, we can see a nice increase in battery life in the next iPhone.