Google has enhanced its mobile offerings to enterprises by introducing push email for iPhone and Windows Mobile devices.

The push e-mail service is available through Google Sync, the technology that already pushes contacts and calendars to phones. Google Sync is free for Google Apps customers.

Administrators can enable push email through the Google Apps control panel, although if companies are already using Google Sync for contacts and calendar, the email feature is automatically enabled, according to a blog from Raju Gulabani, product management director at Google.

People using Gmail and Google Calendar with personal accounts can also use Google Sync to push e-mail and calendar updates to their phones.

Users can choose to sync contacts, their calendar and e-mail or any combination of the services.

Google already offers a connector service that integrates with the BlackBerry Enterprise Server to push Google Apps e-mail, calendar and contacts to BlackBerry devices.

Push email for iPhone and Windows Mobile phones is the latest attempt by Google to move into the business market. It is competing with many well-established providers of push email, including Microsoft and Research In Motion. It is also competing with a number of third-party companies like Good Technology that offer companies a single platform that can push email and other corporate data out to a variety of cell phones.