Object saving is well-supported in Python. There is extensive support in Python for saving (nearly) arbitrary objects to disk files or a database.
Excellent support for documentation of functions and packages in the source code, including automatic extraction of documentation and automatic testing of all examples. The examples are automatically tested regularly and guaranteed to work as indicated.
Memory management: Python now has a well thought out and robust memory manager and garbage collector that correctly deals with circular references, and allows for local variables in files.
Python has many packages available now that might be of great interest to users of Sage: numerical analysis and linear algebra, 2D and 3D visualization, networking (for distributed computations and servers, e.g., via twisted), database support, etc.
Portability: Python is easy to compile from source on most platforms in minutes.
Exception handling: Python has a sophisticated and well thought out system of exception handling, whereby programs gracefully recover even if errors occur in code they call.
Debugger: Python includes a debugger, so when code fails for some reason, the user can access an extensive stack trace, inspect the state of all relevant variables, and move up and down the stack.
Profiler: There is a Python profiler, which runs code and creates a report detailing how many times and for how long each function was called.
A Language: Instead of writing a new language for mathematics as was done for Magma, Maple, Mathematica, Matlab, GP/PARI, GAP, Macaulay 2, Simath, etc., we use the Python language, which is a popular computer language that is being actively developed and optimized by hundreds of skilled software engineers. Python is a major open-source success story with a mature development process (see [PyDev]).
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