First, a little background. I'm a .Net developer (C#) and have over 5 years experience in both web development and desktop applications. I've been wanting to look into iPhone development for some time now, but for one reason or another always got side tracked. I finally have a potential project on the horizon, and I'm now going full steam ahead learning this stuff.

My question is this: I haven't done any C/C++ programming since my schooling days, I've been living in managed land ever since. How much knowledge if any is needed to be successful as an iOS developer? Obviously memory management is something that I'll have to be conscious about (although with iOS 5 there seems to be something called ARC which should make my life easier), but what else? I'm not just talking about the C API (for example, in order to get the sin of a number, I call the sin() function), that's what Google is for. I'm talking about fundamental C/C++ idioms that the average C# developer is unaware of.