In Guido's keynote at PyCon 2013, apparently he talked about adding an
async I/O module to Python 3.4. It looks like his slides can be viewed
here:

    https://www.dropbox.com/s/xknbe58zcvjhzhv/PyCon2013.pptx

...while this is the PEP he's talking about:

    http://www.python.org/dev/peps/pep-3156/

At first glance, the proposed reactor API looks very much like Twisted's
(or, to be fair, GTK's, or possibly any number of other async event loop
I'm less familiar with) but rather than Deferreds and callbacks, the API
will be based around Futures (similar, but not identical, to Python
3.2's concurrent.futures.Future class), and an inlineCallbacks-style
decorator for generators.