Howtoforge posted a guide about setting up the Zimbra Desktop Email Client on Ubuntu 8.04

"This article shows how you can install the Zimbra Desktop email client on an Ubuntu 8.04 LTS (Hardy Heron) desktop. Zimbra Desktop is a full-fledged replacement for email clients such as Outlook or Evolution, offering email, contacts, calendar, documents, tasks, etc. You can use it in conjunction with the Zimbra Collaboration Suite (ZCS) or any other email account that supports POP3 or IMAP."
>>How To Install The Zimbra Desktop Email Client On Ubuntu 8.04 LTS (Hardy Heron)


First Look: Zimbra Web-Based E-Mail for the Desktop
Ubuntu 8.10 Alpha 3 released
Ubuntu MID Edition ships