Anders J. Munch on python-dev correctly says:

You overlooked the words "Standard size and alignment are as follows"
that start the quoted paragraph.  It's a little confusing because
standard size is not the default.  The default is platform-specific
sizes.  Only if you start the format string with >, <, ! or = do you
get standard sizes.

The reference documentation is correct as it stands, and, I suspect,
so is the LP64 implementation.  Doesn't struct.pack('>l',42) produce a
4-byte string on LP64?

The tutorial at
http://docs.python.org/tut/node13.html#SECTION0013300000000000000000%3E
has a bug though: the format string should use '<'.

I believe zipfile.py correctly uses '<' throughout.