Only BlackBerry has true Push email that goes instantaneously the moment you send it. Thats why so many business use BB.
That is not correct. There are various systems which support "true push" (to use your term). Microsoft Exchange supports true push and there are various other OS which do. I use IMAP with my commercial email provider and that supports the IDLE command. With the idle command *as soon as an email* reaches a folder - eg your inbox - a client program is notified etc. In my case my inbox becomes populated with the new mail.
You can read more from this link:
http://www.isode.com/whitepapers/imap-idle.html
I quote:
IMAP (Internet Message Access Protocol) is the best open standard for accessing mobile email. It handles immediate notification as part of general operations and by the IDLE command, which is a widely implemented standard extension to the core IMAP protocol.
Several phone OS provide for IMAP IDLE, including Symbian and even my old Sony Ericsson K790a supported it. Unfortunately Apple for their own reasons do not.