Apple COO Tim Cook said at the Goldman Sachs Investment Symposium yesterday that the iPhone is not "married to any business model".

A multi-carrier strategy for the iPhone is possible, but Apple currently thinks that it makes the most sense from a business standpoint.

The huge number of unlocked iPhones just shows that consumers do not like the locked to one carrier approach. It will be interesting to see how long Apple is holding up their focus on the business side for the iPhone. As long as no other mobile phone company is not catching up and offer a real iPhone alternative, Apple has time.
More details on AppleInsider.

The next big iPhone event is next week on March 6th. Apple is set to reveal the iPhone SDK and a Enterprise strategy for the iPhone.