Based on a recent comment on one of the mailing lists, I spent a bit of time looking into canonical URLs and their implications for how search engines treat versioned documentation.

The most relevant resource for that in relation to the CPython docs appears to be this page on ReadTheDocs: http://docs.readthedocs.org/en/latest/canonical.html

I sometimes encounter direct links to particular 3.x versions in search results, so I'm wondering if it might be desirable to set up the Python 3 docs to report their canonical URL as "/3/<path>", and the Python 2 docs as "/2/<path>".