Palm Treo 650
To setup syncing on the Palm Treo 650, setup your account in Versamail as an "ActiveSync" account. Use your regular username and password. Versamail can be configured to automatically sync the Zimbra ActiveSync account on a schedule as defined by the user.
By defualt the Treo 650 only supports syncing of E-mail and Calendar over-the-air. In order for contacts, task & notes to be sync'd over-the-air you will need to patch activesync  and update VersaMail to 3.5  which costs about $14.00 USD