Still thinking about iPhone versus BlackBerry. The iPhone is great, but I prefer the BlackBerry for business use. The iPhone’s weakest points:
What does a business call look like? You put it on speaker (or headset), put it on mute, stuff the phone away while driving / walking / not paying attention, and unmute when you need to chime in. iPhone is weak in all of these areas. The BlackBerry, on the other hand, is strong - good speaker, physical mute button, easy to carry / stuff in a pocket without accidentally hitting buttons.
What’s missing from the BlackBerry really is just a usable browser. I don’t see why you couldn’t have a decent browser on there. It’d be missing the multi-touch zooming ability of the iPhone, which would be a big deal, but I think that can be worked around. For example, with a single-touch capable touchscreen and a physical button on the side of the phone you could pretty easily zoom in to an area of the screen (put your finger where you want to zoom, push the button).
The iPhone could more easily morph to become a good business phone than a BlackBerry could become a decent browsing device, but with a few improvements BlackBerry could significantly reduce the benefit of jumping ship to iPhone.