Apple's is much less, they make far more off the hardware than the apps, and recent past has shown that developers will develop for the phones even with little chance of making any real money. Apple promotes apps only because they sell hardware, much the way they do with songs on the iPod. They don't care about monetizing them directly, they use them for vendor lock-in.
People are bemoaning changes in the Facebook platform that already exist in iTunes. Apple forces you to give them 30%, Facebook at the worst will do the same. Apple forces even major companies to play by the rules, ditto Facebook. If anything Facebook's are still far less onerous and restrictive.
Facebook's viral spread mechanisms appear to be weakening, but they're still leagues beyond Apple's. Distribution is the #1 problem with the Apple platform and why the real money is in Facebook. Even after the proposed changes FB will still crush them there.
I don't see any reason why nobody could make a couple of hundred million a year on iPod/iPad/iPhone apps, especially as the huge existing installed base of iPods (over 260 million sold) will probably eventually churn into app-capable devices like the current iPod Touch.
http://www.crunchbase.com/company/zynga
Estimated to have made ~$270 million last year: