Great post from MSExchangeTeam describind the default virtual directories in Exchange SErver 2010. This post is really handful when you are troubleshooting publishing on ISA/TMG 🙂
A while ago, we posted the default authentication and SSL settings for Exchange-related virtual directories in Exchange Server 2007. The settings below hold true for Exchange Server 2010 RTM and SP1. You will notice that Unified Messaging is no longer on the list and that is because this virtual directory and the Set-UMVirtualDirectory CMDlet no longer exist in Exchange server 2010. The Unified Messaging mailbox can be created and configured using Enable- or Set-UMMailbox.
Read more at source: http://msexchangeteam.com/archive/2010/09/23/456396.aspx