Interesting. Assume you're referring to the iPhone 4. iMovie has an option to export at three different resolutions (360p, 540p and 720p) so I guess that the iPhone just records at 720p.
You can do this only if you jailbreak it. I forget which file you need to edit. But it still won't give you a switch you can just flip for a different quality.
You can do this only if you jailbreak it. I forget which file you need to edit. But it still won't give you a switch you can just flip for a different quality.