For save scumming in Minecraft:
The world chunks are saved out very frequently (every 30 seconds, by default, I think). The other support files -- ranging from various mod status files to player.dat inventory contents -- are saved at much lower rates. Your player data is only saved when you quit, or when the /save-all command is issued, as far as I can tell.
There is a reason the Minecrack script does /save-off, to disable inconsistent states, followed by /save-all, to get as close to a single-consistent state as possible (*), then a copy/backup, then the /save-on to resume inconsistent but continual saving of chunks.
(*): The question is, if things are altered during the save-to-disk process, does what is out on disk represent the snapshot of how thing were at the start, or does it catch the changes with potential dups/lost things? I highly doubt that Notch wrote state snapshoting, and I don't think it's been high priority for Jeb to fix.