I had an interesting issue reported to me the other day. One of the site administrators noticed that every time he created a new site collection (via self-service site creation), the email address that was populated in the new site collection user list (/_layouts/userdisp.aspx) was not his default SMTP address as specified in Exchange/AD. Instead, it was one of his other SMTP email addresses (we have multiple domains, so each user has 5-10 SMTP addresses.)
Turns out that when you create a new site collection, WSS pulls your email address from whatever is specified on the web application’s root site. At some point, his email address had been manually updated on the root site and therefore every new site was created with that email address.
All we had to do was update the email address that was specified on the root site and all was well. Of course, none of this would be an issue with MOSS, because the SSP handles profile synchronization with AD to keep user information current. This was confirmed by Microsoft support to be ‘As Designed’.