http://docs.python.org/dev/glossary.html?highlight=hashable says:

Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id().

Since x == x returns True by default, so "they all compare unequal" isn't quite right.

In addition, both the above paragraph and http://docs.python.org/dev/reference/datamodel.html?highlight=__eq__#object.__hash__ say:

User-defined classes have __eq__() and __hash__() methods by default; with them, all objects compare unequal (except with themselves) and x.__hash__() returns an appropriate value such that x == y implies both that x is y and hash(x) == hash(y).

This is correct, but may leave some confusion with the reader about what happens to a subclass of a built-in class (which doesn't use the default behavior, but instead simply inherits the parent's __hash__ and __eq__).

Please write what exact text you want to see in documentation.

New changeset 79a021beaf58 by Ezio Melotti in branch '2.7':
#16128: clarify that instances of user-defined classes compare equal with themselves.
http://hg.python.org/cpython/rev/79a021beaf58

New changeset e84c5cf92b6f by Ezio Melotti in branch '3.2':
#16128: clarify that instances of user-defined classes compare equal with themselves.
http://hg.python.org/cpython/rev/e84c5cf92b6f

New changeset d9255c100971 by Ezio Melotti in branch '3.3':
#16128: merge with 3.2.
http://hg.python.org/cpython/rev/d9255c100971

New changeset 1890c63f6153 by Ezio Melotti in branch 'default':
#16128: merge with 3.3.
http://hg.python.org/cpython/rev/1890c63f6153

I addressed the first comment.  The paragraph in datamodel.html looks ok to me, so I left it unchanged.  Feel free to reopen the issue if you have a specific suggestion that could improve that section.