Kinda get the feeling this thread might be against forum policy... but just wanted to ask.... what's the benefit/downside of jailbreaking an iPhone? Keep seeing stuff about it, but never really thought of doing so.
On the plus side you have full access to your phone (your root), and can put non-app store things on it and modify things. The negative aspect is you have to wait for each firmware update to be "jailbroken" before you can upgrade if you want to keep all your new jailbroken stuff.
All kinds of bad things can happen, however it is unlikely with the tested tools from the Dev-Team. They do quality releases and it has always worked without issue for me. My iPhone is jail broken and hacked so that it can be used on T-Mobile. The only thing is that I have to be diligent about making sure iTunes does not upgrade my iPhone and instead I have to wait for the release of a tool that will let me upgrade hacked.
On the issue of voiding your warranty, this would really only be an issue if you couldn't restore to an Apple version of the firmware. That is unless you really truly 100% brick it, but then I'm not sure how they would even know since it wouldn't turn on.
ps - not sure I've ever heard of a case this has happened, so it might not be possible.
I don't see many downsides to jailbreaking. You can always factory restore if you have to send it in. There is one exception though, sometimes some iPhone services might not work correctly. With the most recent firmware, my jailbroken iPhone 3G doesn't have a working GPS. But it's not something I use very often so it doesn't bother me.