We've been trying to figure out the right way to do email and synchronize Calendars. Maybe Google is the right way to do it on the backend?
The candidates are:
* Exchange. This is trusty and reliable. The main issue is do we have to run our own Exchange and Blackberry Servers or do the hosted solutions work. We are trying Applix now and tried Intermedia before, although never got Intermedia Blackberry to quite work. Main question is how well will Apple's direct sync with Exchange work with iPhones.
* Kerio. This is a Mac application that has third party Blackberry integration we need to try. The main issue is how address book synchronization is done, you have to use Apple iSync which is scary given all the problems we've had with it.
* Google. The dark horse. They now have manual synce of calendar with Blackberry so less convenient. On the other hand, they do sync with Outlook. Again manually. So maybe a decent solution.