In November 2005 representatives from the most popular browser vendors (Internet Explorer, Mozilla (Firefox), Opera and KDE) met in Toronto to discuss certain UI changes of their software, to reflect different types of certificates. So they all have some differences about the colors, they agreed, that the address bar should be flushed with different colors, depending on the state of the certificate (trusted CA or not, wrong domain etc), but also the "golden pad lock" will be moved to the address bar. Other ideas which came up in their meeting was, to try to implement some standard, which would reflect the verification level of the certificate. Of course, this is somewhat problematic, since every CA does measure this levels different.
The link for this article located at StartCom Linux is no longer available.