In the language reference, compound statements, class definitions:
"""
Programmer’s note: Variables defined in the class definition are class can 
be set in a method with self.name = value.
"""

This sentence doesn't is not even grammatically valid. It seems that there 
is something missing after "are class".

See:
http://docs.python.org/dev/3.0/reference/compound_stmts.html#class-
definitions

In 2.5, the corresponding text is:
"""
Programmer's note: Variables defined in the class definition are class 
variables; they are shared by all instances. To define instance variables, 
they must be given a value in the __init__() method or in another method.
"""