In light of this now-famous Steve Jobs quote about the iPhone as an open platform (from this Newsweek interview):

“You don’t want your phone to be an open platform,” meaning that anyone can write applications for it and potentially gum up the provider’s network, says Jobs. “You need it to work when you need it to work. Cingular doesn’t want to see their West Coast network go down because some application messed up.”

…I find it worthy to note that the “telephone” in my Nokia N70 is simply another application running on what is, in essence, a small computer: