I use Ubuntu 12.04 and in Nautilus I can see thumbnails of several files including ogg (with embedded artwork) and text files, just like in this screenshot:
It's a nice feature.
I can't see ogg and text thumbnails in other file managers like PCManFM. Moreover, I have another machine with Arch linux and I even can't see them in Nautilus. I can see thumbnails for some other file types (eps, svg, png, jpg or pdf), but not for ogg and text files.
My question is, does ubuntu use a patched nautilus version with extended capabilities to see text and music thumbnailes? And, if so, is it possible to reproduce this extended capabilities to other file managers as pcmanfm?