RIM works by syncing all your email with their servers and then pushing it out to your blackberry with their own protocols. They do this because they were pushing email long before such capabilities came built into MS Exchange.
Wow. What I don't understand is, why do they still do this? Push IMAP is pretty popular, and there's a bunch of other proprietary solutions (as you mention) that also don't have this issue, which is problematic for private enterprise as well as governments.
