One nice thing on Windows is the ability to see useful metadata in the "properties" of a DLL. I think executables and libraries on Linux should have this feature too. It seems to me there should be an ELF section with arbitrary name/value pairs, and some of the names should be standardized so that they can be displayed in file managers like Nautilus, Konqueror etc.
Alternatively if filesystems and file-management tools (tar, cp etc.) evolve to handle metadata robustly, this info could just be stored on the filesystem - in the resource fork, if implemented that way. The trouble with resource forks is that they have to be moved along with the file, so every tool that is routinely used for file management has to support it.