I tend to commit almost everything that doesn’t move to version control, but there’s one major exception: the source data for my website puzzling.org, which is mostly text files. So as to avoid various nuisances to do with calculating data I already have and storing it somewhere else and needing to keep that store up to date I keep track of the time that a file was modified by… asking the filesystem when this file was last modified.
So far so good, and tools like Blosxom do likewise, except that file timestamps tend not to be version controlled, which means if I store my files on more than one machine and rely purely on version control to maintain the date the dates don’t end up the same.
So instead I use Unison, which keeps the trees and dates in sync at the expensive of losing all my history (I also have incremental backups for a couple of months, but that’s a recent addition to my data management). As Martin Pool apparently did at some point, although that was some months before he started writing a version control tool.
Thus, plugin idea for version control system: optional version of additional filesystem metadata, especially times.