When Apple introduced iPhone OS 2.0 for its iPhone and iPod touch handhelds, one of the hottest features was "push" data: the capability to receive instant updates on your phone whenever you received new email, changed your calendar, or performed other tasks needing synchronization (see "iPhone 2.0 Poised for the Enterprise", 2008-06-09).

This feature supported push email for Apple's MobileMe service, for corporate Microsoft Exchange servers, and for Yahoo Mail. Google's Gmail service wasn't supported, but the company has taken matters into its own hands, and now offers Google Sync for iPhone and iPod touch.

Officially a "beta" service (as Gmail itself was for years even after it gained widespread use), Google Sync provides automatic synchronization of mail, contacts, and calendar entries to iPhone and iPod touch handhelds running iPhone OS 3.0 or later. In the absence of native support for Google Sync in the iPhone OS, Google has worked around the problem by implementing Microsoft's ActiveSync technology.

The result should be near seamless and instantaneous communication between the Mail app on your iPhone or iPod touch and your Gmail or Google Apps account. Email messages should now arrive on your iPhone moments after they reach your Gmail account, and changes to your address book or schedule should be reflected just as quickly. It's the same functionality MobileMe users have enjoyed for over a year; it's just now integrated with the popular (and free) Google equivalent services on the Web and on the Mac.

One drawback to Google's use of ActiveSync technology for their push capability is the iPhone's support for only one ActiveSync account at a time. This puts the kibosh on push Gmail for iPhone users who, like me, already access a Microsoft Exchange account for work, or who use such tools as NotifyLink to access other resources using the iPhone's built-in Exchange support.

In the meantime, third parties have developed solutions for push notification of new Gmail messages, such as GPush ($1.99) or Gmail Alerts ($0.99 plus a monthly subscription). These will continue to be a viable option for users who already have an Exchange account set up, or who want actual notifications of incoming mail. But for users with just a Gmail account to monitor, Google's instructions offer a clear way of setting up instant access to your Gmail and Google contacts and calendar.