Undo multiple revisions

1) rollback to revert all last edits of one person 2) open the old version and save it to revert some specific version.

I think you misunderstood. You can undo multiple subsequent edits (you can select a range in the page history, view the diff and use the undo link there), but there is no automatic edit summary. Something like Undo 10 revisions by 3 users or Undo 10 revisions (from 2011-01-01 12:34:56 to 2011-01-01 23:45:00) would be useful.

Since that requires a code change, it should go to bugzilla: unless someone picks it up immediately from here and reports it done within short time.