I know about the iPhone. What do you want to do, and then I can try to answer honestly if the iPhone can or cannot do it - with or without jailbreaking.

If you're a deep down Linux lover, I'll answer that for you now... NO. It cannot do all of the things you want it to do unless you jailbreak it. Then Apple will not support you.

So it just matters. What do you want your phone to do?