An Amiga one has oft been mooted, but nothing yet (its even on the UAE page as iUAE or something like that).
Think there is a version of MAME for Jail-broken phones.
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In other news... am getting a bit pissed off with the iPhone to be honest. Pound for pound, other phones do most everything better beside the App Store and now the multi-tasking has been deliberatly disabled on 3G phones (what i have), its really annoyed me.
Stupid 2 year contract runs out in May 2011 and asked in O2 yesterday, but they will not upgrade me to a 3GS without me paying up the rest of the contract (about £450).
Will probably dump the iPhone in May next year (will be well out of date by then anyway) and if the 4G(S probably by then!) is no good, then I'll go with something that has a better camera, battery life, options etc and just use the iPad for the App Store.