It is not illegal.
Here is the US Gov'ts ruling on it.
No as its illegal.
Illegal inmigrants
i Wouldn't say its bad but if you jailbreak you can get illegal applications and stuff but if you don't you can jailbreak to make tons of modifications to your iphone, i think jailbreak is a good thing.
No. If you are running 3.1.3 (the latest firmware) on any iPhone, then you can jailbreak without unlocking. If you are on a firmware below 3.0, I think you can jailbreak without unlocking. I would like to add that I am pretty sure jailbreaking an iPhone is illegal because of your contract with Apple. Find me on YouTube: TheJailbreakGenius
Us Jailbreak me on the iPhone 4 if you have the firmware 4.0
No but you can jailbreak an iphone or ipod touch but they each have different sites to jailbreak your ipod/iphone
Jailbreak your iPhone
You need to use the program RedSnOw to jailbreak an iPhone 5.
There isn't a jailbreak for the iphone 4 yet, but there will be in the near future.
You need to use the program RedSnOw to jailbreak an iPhone 5.
It is okay to jailbreak your iPhone 3g. The only downside to jailbreaking your iPhone is that you will loose your Apple warranty.
You can not get Siri if you jailbreak a iphone 4. In order to get Siri you have to download the app.