I didn't see it mentioned in this thread but one reason why BB is better for businesses is that its fully controllable and configurable by IT departments. They can decide what access you get from your bb, where the email is stored (for auditing), they can do bulk configuration (change the configurations on all their bb's at the same time), remote wipe (in case it gets lost), encrypt data on the bb, multiple (corporate and user) address books, etc etc. Its not just about push email, which bb does very well.
One other thing where bb's are ahead is local storage. Business people usually travel and being able to take documents down onto the phone and work when disconnected (or when data roaming charges are too expensive) is another big thing. I remember in my last job we would get a podcast sent to us which we could listen to when on a plane or whatever.
Another issue is corporate apps (developed in house) - How can a business get these installed on an iphone. Do they have to give it to Apple and get it onto itunes?
Replacable batteries IS another real issue. We had over 2000 bb's in my last company all the same - same headsets, same batteries same cables, same car kits. Batteries typlically only last about a year or maybe 15 months so getting a replacement from the IT group was easy. Can you imagine telling a sales person that they need to send their iphone off to Apple for a couple of days to get the battery changed - oh and btw - under data protection laws the phone has to be wiped before sending to Apple!!
These are the things that tick IT departments boxes and until Apple gets these issues sorted I don't see major IT departments adopting iphones.