Are you really trying to compare Ebay's stranglehold on the auction market to iPhone's growing, but by no means dominant share of the smartphone market? Nokia is still king worldwide, Blackberry is king of the U.S. enterprise market, and Palm still has over a 10% world market share despite ancient hardware and virtually no OS development in years.

The iPhone's meteoric rise is certainly impressive, but it's a very fickle market, with a lot of incentives for people to jump from carrier to carrier (and often platform to platform) when contract expiration rolls around. iPod/iTunes will provide a bit of vendor lock-in, but I can't imagine EBay-like market dominance is possible in the next five years.