Battery replacement...
I have heard about the 3G battery replacement, and I am rather handy with a soldering iron myself.
And I am aware that preserving my 3G is ecologically the "sound" thing to do.
But I bought the 3G KNOWING it would only really be current for 18 - 24 months. I am burdened with a sock drawer full of unused mobile phones: a BB Bold 9600 (that I really should sell), a 1st gen HTC Touch, a huge HTC WinMobile slider with a 3" touchscreen and a full qwerty keyboard, even a Moto A780 Linux touchscreen phone that is rare as hen's teeth. There are a few even older ones kicking around as well, and an N95 that is missing, presumed dead.
The point is, I only have one left trousers pocket, and I want a current phone in it. The big deal for me is the new camera and flash, funnily enough - I seem to carry either my full DSLR set-up, or just my mobile. Guess which is more available most of the time? So that is something that just replacing the battery will not fix...nor will it get me iOS 4.
But thanks for everyone's input - it is very very instructive. I suspect that Apple will start giving away bumpers soon, but I hate them and probably will just watch the way I hold it, as several have said they do. The fact that Tescos does a 12 month contract for the iPhone 4 may make buying one palatable - you can put up with flaws if you know that in a year it will be replaceable with a fixed model - and I can always sell my old one to keep it out of a landfill! Well, I probably have to, I am running out of room for socks in that drawer...