Blackberry can sync email with Exchange server using Outlook Web Access (OWA), if you get it correctly configured initially. There seems to be a configuration difference between an Enterprise Server Blackberry and a non-Enterprise Server (or Internet email) device that can only be done by the supplier.
As long as you have the internet email confuguration you just go through the normal email setup and specify your exchange OWA address, Blackberry does the rest. In effect a central Blackberry server polls your exchange OWA for new mail and then passes it on to your handheld.
Because OWA and Activesync are closely related this may be what you are hearing about as Exchange activesync.
Ian