Just getting started here -- been writing software for a living for about 30 years and can write Windows stuff in C++ just about blindfolded.
I figure it will take a fair amount of time to get up to speed on the iPhone stuff. Conceptually, if you know C/C++, it doesn't look too bad, but the framework is all different and Objective-C will take some time even if you're an "old hack" at ANSI C/C++.
So yeah, I'd vote with "non trivial" from what I've seen so far if you're starting at ground zero. Lots of resources out there, though.