shuffle2 has successfully ported the original PSGroove payload to Rockbox. Rockbox is an Open Source replacement firmware for MP3 players.
Of the rockbox compatible MP3 players, shuffle2 has tested this on a 5th generation ipod video. He states it will work on all PP502x based targets. Currently it is using the original psgroove payload, without any extra features. However, he has plans to integrate some of the better psgroove payload revisions. When asked which other devices were compatible, he stated: “theoretically anything that rockbox supports (but people with the devices would need to do some simple patches first)”
How to Install Rockbox on an iPod Nano 1G