I agree with Wyatt's point. Wouldn't there be an easy way to reset the last access date on all of the files to say 1/1/2009 on a system then execute a relatively robust multi-user boot (and maybe a world emerge upgrade) and record which files are actually used during that process, then determine which package they belong to and label those with some "level of criticality"?
Its probably also true that this list of files could be part of a "critical system backup" that one could just keep around in a bz2 file for fast recoveries (or even as md5sum's to determine when they might have been hosed by disk errors or viruses) -- or is this something that is already done by some of the selinux options? [I've never used selinux so am unsure of everything it does.] R.
