Interesting piece in the register today. Wendy Alexander, the Scottish labour chief has to explain why she accepted an illegal donation from a tax exile. She's relying on deniability to get her through except that the Word document shows in the track changes that her husbands PC was used to edit it, writing "permissible?" next to the dodgy transaction. A related story might have been if Nationwide had used bitlocker on their PC or HMRC had used IRM on the documents lost. How do you put a price on a feature like Information Rights Management?
Talking of versioning, I often find people are unsure how to enable versioning on a SharePoint document library - it's really easy.
A related very useful setting on the same page under versioning settings is "require docs to be checked out before they can be edited?". This prevents people mucking up the spreadsheet on the share because you can always go back to a previous version and you can see who mucked it up :-)