What does being in the Python core mean? There are two potential definitions:
Documentation says it's available on all platforms.
Documentation restricts it to one of the three platform groups (Unix/Windows/Mac) but implies that it will be available on any OS in that group.
I think the second one is closer to what application programmers thinking about which batteries are included expect. But I could be persuaded otherwise by a good argument.
Actually, when *I* have used the term "core" I've typically thought of this as referring to anything that's in the standard source distribution, whether or not it is built on all platforms.
--Guido van Rossum (home page: http://www.python.org/%7Eguido/)