Google has updated Google Sync, its synchronization service for contacts and calendar events, to include Gmail support on iPhone, iPod Touch and Windows Mobile devices.

"Using Google Sync, you can now get your Gmail messages pushed directly to your phone," said Google Mobile software engineer Douglas Gresham in a blog post. "Having an over-the-air, always-on connection means that your inbox is up to date, no matter where you are or what you're doing. Sync works with your phone's native e-mail application so there's no additional software needed."

Google Sync supports N60 and BlackBerry devices, among others, for contact and calendar sync, but not for Gmail messages at the moment.

Google Sync relies on the Microsoft Exchange ActiveSync protocol, which is supported in a variety of mobile devices.

On Apple's iPhone, configuration is done through the Mail, Contact, and Calendar tab in the Settings menu.

Similarly, Windows Mobile users don't need to download any software.

BlackBerry users, however, have client software to download and install.

Google warns that any push notification system may use more power than manually checking for new messages and may impact battery life. If power saving is a priority, Google suggests turning push notifications off and checking for new content at 30 or 60 minute intervals.

Google also says that Google Sync for iPhone is still in beta and lists a variety of limitations to what the service can do.

Users looking to synchronize Google Calendar and Google Contacts with Apple's Address Book and Contacts applications may wish to consider Spanning Sync 3.

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