I you want details you should research "Exchange Activesync" as that is what Zimbra uses for synchronization. I google search will probably reveal lots of info.
OP: You're not the first one to ask for this functionality with the OSE version of Zimbra. I've seen many many threads asking for the same thing. If anything maybe they could offer one free account with the OSE, anything more than that could cut into profit and I wouldn't expect Zimbra to do that.
Release 6.0.2_GA_1912.UBUNTU8_64 UBUNTU8_64 NETWORK edition + Mobile Option
Activesync with Moto Q9C, HTC Touch Pro, Palm Pro, & Palm Pre