Think enterprise Gmail on steroids. The coolest things on Zimba include their hovers:

Date Hover: Hover over a date in an email and a little pop-up tells you what's on your calendar that day. The same thing works for words like "tomorrow", or "next Tuesday".

Name Hover: Hover over a name and it shows you that person's contact information. You get they phone number when you need it.

It looks like Zimbra is closer to the Web Office ideal, although they have some work to do before blogs and Wikis are tightly integrated into the platform. Emails are sorted archived and tagged. Personally, I think the tagging is overkill for email. It's too much work. But Zimbra's powerful search tools work regardless of whether you have tagged your mail. For enterprise clients to adopt something like Zimbra, they will have to focus on the obvious security issues. With that taken care of, the cost of ownership for a large Zimbra tool looks very cheap compared with thick client solutions. Zimbra does have one easy to fix problem. Their UI is a copy of Apple's brushed aluminum look and feel. It looks too heavy, and a little too complicated. A copy of Gmail's light look and feel will also look more professional. Minor comments on and otherwise stunning indication of what's to come.

I wonder if Microsoft is going to end up becoming a competitor or a buyer?