Heya. I read in some papers (from blackhat!?), that its possible.
But unless this i never found an actuall tutorial.
But here you can find a tut and binaries for installing linux 2.6 in iphone and ipod touch. So with that, you can easily install tools like metasploit, nmap, nessus etc. pp.
But i doubt that the wireless chipset supports injection, so wep hacking will not be possible.