According to the press release, ChAIR Entertainment has made over $10 Million dollars on Infinity Blade in the first 6 months of release.
That means they would have had to make over $16.6 Million total considering Apple's 30% cut. That's over 2.7M units sold.
To put that into perspective, Gears of War sold over 3 million units in 10 weeks, and Gears of War 2 sold over 3 million units in its first month of release.
Now, 2.7M units over 6 months isn't much compared to that, but I'm willing to bet that ChAIR is keeping a far larger share of the retail price than it would have with a game using the regular publishing methods on any of the main platforms.