From InfoWorld article:
"McAfee Inc. is planning enhancements to its recently acquired SiteAdvisor software that will allow the Web-rating application to block inappropriate Web sites, offer safety ratings for online transactions and rate Web links that appear in e-mail and instant message windows."

These features will be reportedly added over the next year.

Oops! And the source link:
http://www.infoworld.com/article/06/06/09/79162_HNmcafeerateboost_1.html