I've started reading the design pattern book by the GoF. Some patterns seem very similar with only minor conceptual differences.

Do you think out of the many patterns some are unnecessary in a dynamic language like Python (e.g. because they are substituted by a dynamic feature)?

Peter Norvig demonstrates that 16 out of the 23 design patterns found in the GOF book are invisible or simpler in dynamic languages (he focuses on Lisp and Dylan). 

Since you mentioned Python, there is a nice presentation by Alex Martelli about the topic. Also related with Python, there is a nice blog post demonstrating six design patterns in idiomatic Python.

I also keep a github repository with implementations (by other people) of the most common design patterns in Python.
