If I listen carefully, I think I can hear the Zimbra programmers weeping.
I've not checked out Android yet, but my gut instinct on this would be to ask that the iphone features be completed before adding code to support another mobile platform. The android phone will likely support activesync soon, and then the work done to make zimbra support all the nuances of activesync (remote wipe, shared calendars, GAL etc) will become available to Android by default.