Python is named after Monty Python. Its faster to code but may run ever so slightly slower than C++ so you can use python for EVERYTHING except where maximum speed is the key issue. python can be used to build everything you ever imagined! it is also simpler and faster to develop. Your original source code (py) is compiled to byte code (pyc) then it can be executed by PVM (python virtual machine).
CPython is the standard python compiled in C, Jython implements Python for Java, IronPython implements Python for .NET environments. These are just alternative compilers. As for variations in execution there's things like Psyco, Shedskin, and frozen binaries.
Download it here: http://www.python.org/download/