Well, some really smart guys have figured out not only how to get linux onto the 4G iPods, including the iPod photo.. but they've managed to get video to play! They're still working on the audio, so right now it's only a specific kind of video that'll play (24bit, uncompressed), with no audio.. but still, it's pretty damn cool!
I did it tonight, and it was pretty easy. I had to re-install v1.0 firmware onto my Photo, so that was a bit tricky, but I managed to figure it out, and created a nifty updater that re-installs the old firmware without deleting anything.
Anyway, here's the link to the tutorial for install linux:
http://www.club60.dk/exdev/?p=20
And the info on playing videos:
http://ipodlinux.org/Video_Player