Hey,
Yes it is possible, I just tested and it does work in Outlook 2007 for sure.
First you need to have the ZCO installed and the Zimbra profile setup first then go into Mail under control panel.
Select the Zimbra Profile and click on Properties. Click on E-mail Accounts. You will get a new window that shows you the Zimbra e-mail account. Click on the new button and input the info for the exchange account you wish to add. Outlook will test the settings when the test is complete go ahead and open outlook and let it sync down the new account. Everything should be working correctly. I do not recommend doing this as something could go wrong and wreck something in the Zimbra account also its usually best to keep seperate profiles.
Good Luck
