This does exist.
ongame/pacific definitly have mobile versions.
AP/UB also have them i think.
However I have yet to see one for the iphone that i have been able to get working
pacific claims to be iphone compatable but i couldn't get it to work. If anyone has got one working on an iphone post
There is also rumour that FTP is neg. a deal for FTP to come prepackaged with the iphone.