Zimbra Mobile enables you to sync over-the-air with ActiveSync devices like the iPhone v.2.x (and v 3.x... although Zimbra supports CalDav with iPhone 3, too).  Zimbra Mobile is included free with 01.com Zimbra cloud hosting mailboxes purchased with a prepaid annual term.

"Zimbra Mobile for Smartphones enables two-way, over-the-air synchronization of mail, contacts, calendar and task data between the mobile device and the Zimbra Server. It features push email, which sends messages in real time to your device when it arrives on the Zimbra Server."  Read more here.

Zimbra Mobile is a license purchased through 01.com or Zimbra that enables a Zimbra server installation to sync with ActiveSync devices, such as Windows Mobile, Palm and the iPhone 2.x/3.x software, including Calendar, Contacts and Email.

Supported devices are ActiveSync compatible and include the iPhone v.2 and iPod Touch v.2, Treo 650, 680, 700 w/p, Nokia E-Series, Motorola Q, and Samsung Blackjack (all Windows Mobile 5 devices).  A list of supported phones is linked here.

Syncing email, for example, syncs messages you've read and sent so that messages appear as read in both your mobile device and inbox, and sent messages from your mobile device are viewable in your sent messages directory/folder from your desktop, and the Zimbra webmail interface (your web browser).

Zimbra Mobile may be licensed on a per mailbox basis with month-to-month terms through 01.com's shared hosting environment, where it's also included free-of-charge with annually prepaid Business Zimbra Hosting, or for an annual or perpetual support fee for Zimbra installations of dedicated servers and other servers maintained or just licensed at customer offices and third-party data centers.

Please note Blackberry sync is not included with Zimbra Mobile, nor is Zimbra Mobile necessary for Blackberry sync when used with NotifyLink.  See Pricing.