"It's not often we encounter a product that wows us, especially in the messaging and collaboration space where Exchange is the standard bearer and the competition is often a pale imitation with a few minor additional features tossed in.
Zimbra is an exception. The open source collaboration suite (whose name comes from the Talking Head song of the same name) has been available since August, but earlier this week it took a great leap forward when it announced the product, currently available in public Beta, will be generally available next month..."