I notice that recently there is a new "undo" link appearing when viewing old diffs. Strangely, it only appears for diffs other than the latest one. It looks like what it does is let you remove text that was introduced in an old revision but subsequently "consolidated" by a later edit. I have two questions about it:

1) Is there any documentation on it, and if so, could that be linked to from the text that says "The edit was successfully undone. Please click save to apply this change." (and also from the error message you get when it can't undo due to intervening edits)

2) What's the rationale behind not making it available for the latest edit? Presumably this is a political sensitivity about not giving rollback to everyone, but it's a bit odd to effectively give rollback for old edits, rather than for all edits, which would be much more useful. Could we perhaps trial "rollback for everyone"?

Steve