Part of the problem isn't the raw numbers, but the perception of each platform. With a closed ecosystem, the iPhone is not as vulnerable in the press to claims of “rampant piracy” as to other platforms. Given the Nintendo DS and PSP warez scene, I'd say they were at similar levels, but the PSP carries the “I'm a pirate target” flag while the DS keeps relatively quiet.
Nokia had to deal with this in the first generation N-Gage and never really solved the problem beyond “you might not be able to connect to the Arena with a pirate copy” but the machine was tarred and feathered and never recovered from the stigma.
So what can be done? This is a tough area, because there is no magic wand, and the rule is simple. No matter how big your team, or how much you invest, there are billions of people in the world, and enough free time to crack any system. And it takes just one to break it, and the copy is then released for everyone. The internet is rather good at copying digital data once it's hosted in a single place, you know.
Something for authors and developers to consider is that the piracy scene has created a phenomenally efficient distribution system – if you want to get something out there, the quickest way to do so is have it pirated. The catch of course (rather like the NHS) is that these copies are free at the point of download; so to have some sort of income stream, the cash and the user need to be separated a little bit further down the line.
World of Warcraft does this really well. It doesn't care how you get the client software, because once you have it you'll be logging on and paying a monthly subscription.
Ad-supported software also follows this money. Yes, it's a much smaller income per user, but it does work and uses piracy to your advantage. And ad-supported is something that the iPhone ecosystem does very well – witness Google's purchase of AdMob recently as evidence that there is money out there.
Or you could go down the route of having some in-game credit system which would allow a virtual currency to be spent and traded. Second Life has a huge economy built on this principle and many social games (e.g. FarmVille on Facebook) have the ability to buy additional credits to help you advance in the game at a faster rate.
Yes, piracy is around but the answer isn't as simple as “let's just stop it.” Rather than that, it's time for the industry to get creative alongside all those people who remember that buying a developed application helps you get more applications developed.
-- Ewan Spence, Nov 2009.