A TechNet Wiki article has been created to explain how to create a mail contact entry using the CSVDE utility for Active Directory.

http://social.technet.microsoft.com/wiki/contents/articles/how-to-import-mail-contact-into-active-directory-using-csvde.aspx

This article was created because of the popularity of a related forum post

http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/e4532b45-1f0a-4fb7-9fad-8f56a58baa5f