Google has announced the availability of Google Sync, which will provide push synchronization for a user’s Gmail contacts and/or Google calendars.
Sync uses push technology (Microsoft ActiveSync©) to automatically synchronize your Gmail contacts (using the ‘My Contacts’ group within Gmail) and/or your Google Calendar events in the background.
This is a great feature for non-MobileMe subscribers, or any other user who still relies on tethered syncing to keep information up-to-date. No word yet on adding push Gmail to the mix, but there is no reason to think it is not in the works.
One issue bound to arise for many users is the current limitation of a single ActiveSync account configured within the iPhone software. So if you are using your iPhone in conjunction with your employer’s Exchange mail, for example, you probably are already utilizing that single ActiveSync account, and will not be able to add this Google Sync account.
I have run into this limitation previously in experimenting with other ways to sync Google calendar. I wanted to try NuevaSync for over-the-air Google calendar synchronization, but alas, keeping my work account configured is too important.
I have not been able to track down an official reason why the iPhone is limited to one Exchange account; perhaps it is a licensing issue.

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