I have shot full time for a living for over two decades, done very well. After shooting digital for nearly 18 years, I have gone mostly back to film for fine art and some magazine work, but I do pull out the digital for certain things.
Megapixels matter, to a point. What the iPhone has over many digital cameras, including my high end Nikons and even my new fave, the Fuji X100, is "Mojo".
It just has a unique combo of enough resolution paired with a sharp lens and a great way of drawing in light. When in Paris last year, I encountered a large protest that had blocked off a major intersection. I was in my 6th and final year on a book project shot on film, I only had my iPhone4 as a digital. I shot the protest and moved the photos to my agency in New York, we made three newspaper covers and made several other sales due to speed over file size.
But the best return on my iPhone investment came this year with a show of 22 images from my phone, most were 9" x 9" prints but we also did two 30" x 30" prints that held up fantastic. I made enough money off of this
show to pay for new iPhones for many years to come.
Out of some 8 cameras in three formats, the iPhone 4 is one of my favorites. So since I am holding out for the 5, I ordered my wife the 4S. And folks, it does not matter how many megapixels it has, all that will ever matter is how talented you are and how you see the world.