I'd like to thank the Zimbra employee/dev who corresponded directly via email and even took his own time, after work, to help for several hours on a problem/issue with the beta Outlook 2007 connector. He got it working and the user - our CEO - is quite happy with the results. Our CEO was eager to get Outlook working, but even before then, was impressed with the web interface and the conversation-grouping, and already felt more productive.
This level of support of the product - especially in this instance, but by no means limited to it - just reinforces the fact that we've made the right choice in starting our migration to Zimbra. We're not a complete success story yet - still existing between Zimbra and our legacy mail system, but I can feel confident in the product and the people behind it. And I'll be contributing to the forums as I can, for they've already helped me.