I'm studying Smalltalk right now. It looks very similar to python (actually, the opposite, python is very similar to Smalltalk), so I was wondering, as a python enthusiast, if it's really worth for me to study it.
Apart from message passing, what are other notable conceptual differences between Smalltalk and python which could allow me to see new programming horizons ?
The language aspect often isn't that important, and many languages are quite samey,
From what I see, Python and Smalltalk share OOP ideals ... but are very different in their implementation and the power in the presented language interface.
the real value comes in what the subtle differences in the syntax allows in terms of implementation. Take a look at Self and other meta-heavy languages.
Look past the syntax and immediate semantics to what the subtle differences allow the implementation to do.
For example:

Everything in Smalltalk-80 is available for modification from within a running program

What differences between Python and Smalltalk allow deeper maniplation if any? How does the language enable the implementation of the compiler/runtime?
Differences between Smalltalk and python?