Interesting. Everything seems using the same define that is the data format for the site. So it is strange that they are different.
[edit] Even more interesting is that the format showing is different from the Option format--"Feb 25, 2008"
[re-edit] And all these formats seem working locally for me
Just to note: The site indeed showed dd/mm/yyyy although set to mm/dd/yyyy yesterday. I had therefore changed it to Feb 25, 2008 format on the site itself yesterday to avoid confusion. The lastest articles on the forum sidebar are done via the rssparser we use in hte admin overview. Maybe its format is hardcoded, I have not looked yet.