Our company applied for the enterprise beta version, im not sure our application would be approved, but if so that would be a GREAT move for the business world. Right now, even with the limited capabilities in business compared to the blackberry, there is A LOT you can do. HOWEVER, we are a small business, and nothing like the giants out there, so the iphone is BETTER than good for our situation. The web apps that are out now that let you do work orders and such through one click are GREAT, and the quixkbooks access is also a great application to have.
I think that with some more apps and the new enterprise coming out, it will give blackberry a run for its money, thats for sure.. but the above poster is right, for a big company to change its way of communicating completely just because there is a shiny new device out there is very unlikely.