Emulating an iPod

I might be revealing my ignorance here, but just as disk-based iPod were, also, generic USB or FireWire storage devices, I understand the new iPod shuffle is also a generic USB flash memory thumb drive.
So, that must mean that, in addition to the usual circuitry to make the drive appear as a storage device, there’s some litle bit of identifying code to make the drive appear as an iPod to iTunes?
If that’s the case, can someone hack either iTunes or the generic windows USB mass storage driver (for which source is available) so that any MP3 player that can appear as a USB thumb drive can also appear as an iPod to iTunes? I think there’s a substantial market, at something like $20 a pop, to selling “connect your flash memory MP3 player to iTunes”.
I’d lazyweb the request, but surely someone’s already done this and I just don’t know about it and can’t find it.