NS 2.0.9.4rc1, Fx 3.6.13, new profile, remove (msn.com, about:blank) from the whitelist.
- login to https hotmail: https://mail.live.com/
- once you get to the inbox, you'll see that the two ad iframes (1 - lower left, 2 - right column) are untrusted. They both have the url of their parent (InboxLight.aspx), which is trusted.
- add about:blank back to the whitelist and refresh, the iframes now appear to be trusted