The iPhone virtual keyboard could prove to be a huge success for a few reasons:
1. The iPhone error correction is a big improvement. I think we have all collectively forgotten that it seemed like a crazy idea to spend significant amounts of time emailing with our thumbs! People will get used to typing without tactile feel if Apple does a good job with error correction. Anyone who has spent time emailing with a Blackberry or Treo knows that errors are the name of the game (Blackberry still doesn't have spell correction and the Treo auto correct is sort of a joke). We have all probably received emails from Blackberry users with the auto signature something like: "Please excuse errors, I sent this from my Blackberry." If Apple's error correction is as good as it is rumored to be, the experience of emailing on the iPhone could be fantastic and more productive (less time correcting messages, more time communicating). It reminds me of debates
I used to have in the late 80s with DOS users who were convinced that their text interface was far superior. The "interface" is not the tactical feel of the keyboard - but the whole experience of entering data and accomplishing tasks with the device. The "enter data" interface for any tiny device like a phone is input + error correction, so if the input (the on screen keyboard) is ok and the error correction is much, much better, people will adopt it very quickly. The whole experience of the interface will feel much much better even if the tactile feel is different.
2. Apple will probably roll out over-the-air (OTA) syncing for iCal (and Address Book). Sure the tiny little keyboard is nice, but what made the Blackberry and Treo really successful is OTA. This is a must have for business now because we do everything in real time (change meetings, contacts, locations, email etc.). Apple is addressing the email part of OTA by supporting IMAP, which is great. And it looks like OTA for iCal might be in the works. iCal in Leopard combined with the new iCal Server can do group scheduling, auto schedule (pick a meeting time when everyone is available) and two-way editing (your assistant can edit your iCal).
I would be surprised if the launch of Leopard didn't include a serious update to .mac with hosting for iCal Server (for a fee of course). It should also include a much needed upgrade to .mac sync (an hopefully end the endless arrows chasing each other as you wait for the sync to finish). The next logical step is OTA with iPhone.
3. The market Apple is targeting is huge - and it is not Blackberry users. The hard core Blackberry users are on a corporate Exchange network. They can complain about the lack of keyboard all they want, but they are a slave to the IT department that runs the Exchange server (no real Blackberry user POPs their email). So if they wanted to get off the Blackberry they couldn't anyway. So Apple probably isn't targeting them. Exchange is an insanely expensive solution (software, hardware, IT staff to run it) and ripe for an alternative, so if Apple gets OTA right with iCal and iPhone, you could see some migration, but probably not much in v1.0.
The second target market is "hosted" Exchange servers (like mi8). These work well and are less expensive, but they still ain't cheap - not by a long shot. So Apple could take some share here as well.
But the third, and I think primary, target market for the iPhone is the gigantic number of small businesses who don't have Exchange set up with Blackberry or GoodLink (Treo). If Apple penetrates this market with a simple hosted OTA iCal-iPhone solution it could be a huge growth driver - they buy the iPhone and pay a monthly fee for OTA based on .mac. And regardless of the price of the iPhone, it will be a huge cost savings over any Exchange server solution.
If the browser is as good as it looks, you can even do a totally free version of OTA with Yahoo IMAP for the email and Google Calendar for group calendaring. Tough to beat that price.
So Apple's strategy doesn't have to be "kill the Blackberry". It's probably more like "Blackberry for the rest of us."
I originally posted this in the comments of good discussion on Steven's blog.