I've solved the battery problem. I use this: iBattz battery case. This is a battery case that you can swap in a new battery and take out the old one. I use this with the quad lock stem mounting system to mount this case. All you do is stick their universal adaptor on the back of the iBattz case and you're good with about 225% of the iPhone battery. You can bring as many of the extra batteries as you want - they are about the size of half a business card and about pretty thin - you could bring several easily in a jersey pocket and not even know you have them.

I use Cyclemeter as my bike computer. I used to use a Garmin but since I'd have to bring my phone anyhow, and because the display is so much better on the iPhone I ditched the Garmin. With the quad lock system I also don't have to put it in my jersey pocket either. This works just great and you can set yourself up with (essentially) infinite battery power.

J.