iPhone users should track developments closely, as hackers and crackers are actively exploring security developments to discover weaknesses.

Hackers gain shell-level access on iPhone
http://blogs.techrepublic.com.com/tech-news/?p=775
http://www.engadget.com/2007/07/06/iphone-...or-shell-access

QUOTE
Well, that didn't take long -- the hacker crew of IRC channel #iPhone has managed to enable shell access to the iPhone just a week after its release. There's not a lot to the hack -- the iPhone's 30-pin dock connector features the same pinouts as the iPod, so creating a serial connection simply involved connecting up a resistor, ground, and RS-232 level converter and running a few commands from iphoneinterface. The resulting shell is pretty basic, but features a TFTP client -- meaning that we should see a flood of attempts to open the iPhone up in the coming weeks (as if we wouldn't anyway).