saving POWER!!! That's what it's all about!
Every macintosh computer has the ability to invert color simply by pressing: command, option, control, 8 sequentially. On a portable machine, this saves tremendous battery power while reading text, or anything where there is a LOT of white, because white uses more brightness.
The point of it is for text based stuff or simple internet browsing where text is the main thing where there is a bright white background. Of coarse you wouldn't use it as the main GUI for all day long! lol!
It is also a LOT more easy on the eyes, and STILL doesn't use as much power when set to the highest brightness setting.
There needs to be a jailbreak TWEAK (NOT a theme!) that inverts all colors on an iPhone. That would save TREMENDOUS battery life, especially when I'm reading my pdf textbooks for a couple hours!
Of coarse apple ONLY put this on the 3gs, the new ones don't have an unlock/jailbreak (That I'm aware of, if anyone knows, please tell me, for a macintosh computer) and it's a lot easier to sell it to older people who would have vision problems and what not.
A lot of iPhone purchasers also do not own macintosh computers, so they are unaware that an Apple computer has this same exact accessibility feature.
I have an iPhone 2g, unlocked/jailbroken with redsn0w.