Google has added GMail push support to their Google Mobile Sync product,
which is based on Exchange Activesync, acting as a faux Exchange server on
Activesync-capable mobiles like Windows Mobile, iPhones and Symbian S60
phones.

For those of us not using Exchange, this gives OTA push sync with GMail,
GMail contacts and Google Calendar.

http://googlemobile.blogspot.com/200...l-support.html

While this is particularly good news for GMail/GCal users, with the Google
Calendar sync plug-in for Outlook and any third-party GMail Contacts
plug-in, this can allow free Exchange-like OTA sync with your Outlook PC as
well.