Push email has always been a matter of pride for the road warriors. Having email delivered to your mobile device the instant it lands on your mail server - that's like ultimate nirvana! RIM had the first popular commercial implementation with their BlackBerry enterprise server and BlackBerry devices. Windows Mobile introduced it with WM5 MSFP (Messaging and Security Feature Pack) which works with Exchange 2003 SP2 and (now) Exchange 2007. Steve Jobs announced push email using Yahoo for the iPhone which was probably the first announcement of push-email for non-enterprise (and free) email provider.
Well, with Windows Live Hotmail and WM6, we have push email support for free! And it works pretty darn well. If you have access to a WM6 device, sign up for Windows Live Hotmail (www.hotmail.com). On your WM6 device, open up Windows Live
Follow the wizard to enter your Live credentials and configure your device to use Live services (Messenger, Mail, Contacts, etc).
After you have configured your device to use Live, click on Menu and select options
Select Sync Schedule
Under Sync Frequency, select As Items Arrive
Thats it! Your device is set to have the full goodness of push email. Who said nirvana was difficult to achieve :)