As per request from http://wordpress.org/support/topic/date-of-last-login?replies=4#post-5163689 this request.
When I use the SB login widget the date of last login, is actually the date of this login. So it always displays the date of the login of this session.
I did create a custom (dutch) translation, I do not know if that affects the workings of the widget.
[Moderator Note: No bumping, thank you.]