First of all, if you're writing apps for the iPhone, you have no choice. Objective C is your language.
If you're speaking of programming in general, then there's a discussion to be had. Languages are just tools. Different ones have different strengths and weaknesses that lend themselves to being commonly used for different sets of problems. That said, Python's a pretty good general purpose language, and the fact that it has VM support for .net, Java, C, and, well, Python (yeah Python in Python, let's keep moving ...) means you'll probably be able to find a way to use it in most environments provided the pointy-hairs approve.
Don't pick a language because of its age. Pick it because it fits your set of problems.
Starting out, I would absolutely recommend a scripting language (of which Python is one), but I'd actually point you to
http://www.eloquentjavascript.net rather than
http://www.diveintopython.org simply because I don't know of a good beginner reference for Python and because a browser is a nice place to learn a language.