Checked out document

What happens if a document is checked out but the user who checked it out is no longer available? Can the system or organization administrator check that document back in?

Clues for the clueless appreciated,

I know in v7.1 you can "Undo Check Out" if you log in as the Organization Admin.
All other users will get a red error showing who checked it out but the Org Admin it will just Undo the check out.