On TUAW, the comments on a post[1] about removing the DigiNotar certificate indicate that all you really have to do is quit and relaunch Safari to get it to notice that the certificate has been marked as untrusted. How did this article decide that EV-SSL was to blame?
[1] http://www.tuaw.com/2011/09/01/how-to-get-rid-of-diginotar-d...