What version(s) of Python are pre-installed on OS X 10.9 Mavericks?

It's on 2.7.5.

Python 2.7.5 (default, Aug 25 2013, 00:04:04) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 

My MBA, which has been incrementally upgraded from 10.7, contains the following versions of Python:

Python 2.5.6 (r256:Unversioned directory, Aug 25 2013, 00:03:43)
Python 2.6.8 (unknown, Aug 25 2013, 00:04:29)
Python 2.7.5 (default, Aug 25 2013, 00:04:04)

Being that they have the same build date it would appear that all versions of Python have been updated with Mavericks.

Python 3 is not installed on my machine.

On my rMBP, my upgrade from 10.8.x to 10.9 lists the following versions of Python in /System/Library/Frameworks/Python.framework/Versions:

2.3, 2.5, 2.6, and 2.7.

There is no Python 3.0 listed here for me. One can use MacPorts (and probably Fink or homebrew) to get Python 3.