One more challenger for the iPhone

New Apple (AAPL) challengers appear with great regularity. Research in Motion (RIMM) has launched consumer versions of its BlackBerry. Palm's (PALM) Pre is meant to take iPhone share. Samsung built a phone called the Instinct to help Sprint (S) challenge AT&T's (T) efforts to take market share via the iPhone.

All of the competition has one thing in common -- they have done almost nothing to throttle the iPhone's success. There are several theories about why the Apple product sells so well, and most of them are likely to be true. The phone is easy to use, even though it has a large number of features. AT&T has made certain that the handset is not too expensive by underwriting the cost to its subscribers. Apple updates the phone with new features. The iPhone App store has over 50,000 software products to enhance the smart phone's usefulness to consumers and businesses.