Mozilla CEO John Lilly and VP of engineering Mike Schroepfer said that Apple’s software requirements for the device are too restrictive, and as such, they will not be making Firefox for iPhone, at least in the near future.
According to John Lilly - "Apple has not written a license which allows Firefox to run on the iPhone."
"Android and iPhone are closed platforms. There are carriers and device manufacturers who are more open with their platform, and we'll do well there - the Nokia N810 internet tablet, for example. People can just take the (Firefox) code and run with it, so there's a lot happening that we don't even see until it shows up... XUL (the language in which Firefox's user interface is written) makes it easy to experiment on mobile devices. That's our main advantage on mobile platforms." - added Mike Schroepfer.
P.S It should be noted that 10th anniversary of Mozilla will be celebrated on Monday. References: