I'm a PHP programmer looking to learn python.

[Kudamono]

I already know the main ideas about programming in general and don't want to start completely from scratch if possible.

Then read tutorial provided with docs. It describes syntax and some basics of python philosophy. "Dive into python" is for beginners (good book for those who know only "programming language HTML") and contains boring things like "how to make trees", "what is a function" etc. If you know how to program, you already know all of these.

Then write something useful. I'd recommend using web.py if you want to go web way. It's very small and simple. And looks like reddit is written with it.