I was just browsing the internet and took a peek at Exchange 2007.
It seems like they are adding Unified Messaging which basically means you can access your voice messages, emails and faxes within outlook.

What is the status of this type of integration is Zimbra ?
I know there is a zimlet to talk to Asterisk but are we able to view and hear our voicemail in zimbra ?

Fax is interesting too ...