Once again got close to committing this, but then realised it is missing all the necessary documentation updates for a core language change.

I have uploaded a patch that includes all the changes from Bitbucket as well as the subsequent fixes to avoid modifying sys.stdout when the tests are run and to comply with the whitespace rules set up in the source control hooks (the ACKS, NEWS and a placeholder in whatsnew are also included).

What's missing are updates to at least:

http://docs.python.org/dev/tutorial/classes.html#generators
(a simple example showing delegation should suffice there)

http://docs.python.org/dev/reference/simple_stmts.html#the-yield-statement
http://docs.python.org/dev/reference/expressions.html#grammar-token-yield_expression
http://docs.python.org/dev/reference/simple_stmts.html#the-return-statement
(the language reference must be updated for a post PEP 380 world)

There are likely other places that should also be updated, but these are the critical ones needed before the patch can be included.