We've been able to run Linux on old iPhones for quite a while now, as can be noted from the defunct iDroid project, which managed to successfully port the Linux kernel and Android userspace to the iPhone 2G, 3G, 3GS, and 4 using OpeniBoot. However, this is quite a nice advancement for those of us in the emulation community.
Disclaimer: I'm working with some other team members on the revival of the iEmu iPhone emulator.
Disclaimer: I'm working with some other team members on the revival of the iEmu iPhone emulator.