When viewing the difference between current revision and previous revision of a page where the current revision is deleted/empty, (?do=diff) the dates associated with the revisions are wrong.
The current revisions get "1970-01-01 01:00" (unixtime) whilst the previous get the one belonging to current.
Examples:
Devel:
http://wiki.splitbrain.org/bla?do=diff
2006-11-06:
http://wiki.zyberdog.dk/testpage?do=diff
To see the actual dates of the revisions, click [Old revisions] on each of the sites above.