I've heard Metasploit runs on iPhone. Not great but it'll run.
I usually carry a couple SSH,VNC,RDP clients. Easily found in the AppStore.
"Veency" is a pretty good VNC server for the iPhone.
There are a couple of pretty decent Network Scanners in the AppStore that can map out printers and various NICs.
Pirni is a pretty good "packet capturing"-software that runs natively on the iPhone. However, when analyzing the packets I would recommend a computer. :-)
Hope it helps!
/ gEEEk