I mostly lurk now, having pretty much retired from KoL itself, but I thought I'd chime in a couple things (then run and hide away again).
1) I agree w/ roippi about tortoiseSVN; I know nothing about SVN, not really a coder myself, but I used it a few times and found it fairly newbie-friendly. I also hear it "scales" well for those who want to become power-users, eventually, but can't speak to that.
2) Providing release notes as a data file seems like a nifty idea. Somebody should write a relay override that lets you view release notes, and it wouldn't be too onerous to come up with a standard format so that it could read all the notes it "finds." Tracking where to look for such things could be an issue I guess, but otherwise that seems like a good solution to me. Then, the cli output could just notify of changes, and the user could run said relay if and when they wanted further info.