All your mail accounts can get push notifications. They're not the kind that pop out into the middle of your screen like a text message, but they make a little number on the top left corner of the Mail icon on you home screen. You can change that setting in Settings>Mail, Contacts, Calendar then tap on fetch new data and make sure it is set to Push. I hope thats what your looking for. Otherwise, you'll have to wait until IOS5 with the Android style drop down menu with you notifications. That will will have your Emails