In a survey of iPhone owners, Rubicon Consulting found that a third of iPhone users carry a second phone in addition to their iPhone. I'm one of those folks: I have a T-Mobile phone that I use for personal calls; I use my iPhone as a business phone and for mobile Web and email. I didn't want to break my T-Mobile contract and I'm happy paying for a second phone to keep work and home separate. I didn't think I was the only one with two phones, but 33 percent seems surprisingly high. Here's something the survey didn't tell you, but you might have guessed: iPhone users have lots of disposable income.