http://docs.python.org/tut/node11.html talks about old/new style
classes. But there is no any explanation what it is. The same for
http://docs.python.org/ref/node33.html
My suggestion: refer to http://wiki.python.org/moin/NewClassVsClassicClass

I think this can be closed as 'out of date'.  The language reference
chapter has a section on old and new style classes, and in the tutorial
section the reference to 'new style class' is hyperlinked to a glossary
entry that in turn contains a pointer to that language reference section.

* http://docs.python.org/reference/datamodel.html covers new style and
old style quite well.
 However, for the sake of the reader who reads it top-down, it will be
nice to add internal cross references (to
http://docs.python.org/reference/datamodel.html#new-style-and-classic-classes)


* http://docs.python.org/tutorial/classes.html mentions old-style
without any hint to the reader what it's. I suggest to add a link to
http://docs.python.org/reference/datamodel.html#new-style-and-classic-classes.

The new docs already have glossary entries that point to the datamodel doc.