Exchange Server 2007 and wild card certificates

This topic came up in a discussion list that I am on and I thought it worthy of blogging. Some Certificate Authorities (such as DigiCert) offer a "wild card" certificate. While these seem to work fine for web sites, they are problematic with other Exchange Server 2007 technologies such as POP3, IMAP4, ActiveSync (Windows Mobile 5 devices), and Outlook Anywhere. It sounds like these should be avoided for Exchange servers and instead use certificates with subject alternate names (SAN certificates or now called Unified Communications certificates.)