s0nykus i keep my os x stuff in
http://nawcom.com/osx86.
As for distributions, be sure and understand that there really isn't anything different when it comes down to distributions. I could put a Linux kernel together with my own customized GNU userspace environment and call it Nawcom Linux. It's still the Linux kernel with GNU userspace, just like Ubuntu, Fedora, Slackware, Debian, Gentoo. So the answer is no - you really can't tell what distribution it is, unless you want to specify it in the bootloader regarding the OS title which the bootloader can try and interpret, or add additional code for accessing files inside the ext* partition, which would be too much work and not worth it in my opinion. So ideally, no. There isn't any set standard for defining the distribution title via files.
If you look at the diff file you can see that this uses the same exact technique that is used for Linux detection, magic number values. Look at ext2fs.c, openbsd.c, freebsd.c and the functions FreeBSDProbe(), OpenBSDProbe(), and EX2Probe(). There is only one magic number value for Linux - not a special one for Ubuntu, Slackware, Fedora, Redhat, etc. The magic number is always the same regardless of Linux distribution. There are no "distributions" of BSDs per-say, as FreeBSD and NetBSD, OpenBSD, DragonflyBSD are all completely different OSs with different kernels, though of course all come from a common ancestor.