For those learning Python, personally, I would recommend Learning Python by Mark Lutz but as a companion book, this Python Cookbook is wonderful!
It'll help you learn a little bit about Python if you're starting out but once you get the basics down, the Cookbook series are THE way to go.
Working with file I/O? This book has a recipe for you. Doing networking? This book has a recipe for you. Need to process through data from various file formats? This book has a recipe for you.
If anything, look through the TOC to see if there's anything that might be useful and chances are, you'll find it in this book.
I would definitely recommend this to anyone who uses Python or will be using it more in the future.
Disclaimer: I received an electronic version of this book because I am a part of the wonderful O'Reilly Blogger Review Program. These are just my opinions of the book.