> There is a 5.3.X and a 5.4.X version happening concurrently?

That's not uncommon, and useful for people in production who'd still need bug fixes but don't want to risk breakages due to new features (and potential grammar changes) and the like. Language versions often have end-of-life dates which follows the release of the next version (and even the one after that) by a significant amount of time (Python 2.6 will be EOL'd in October 2013, even though Python 2.7.0 was released in July 2010.

FWIW (and ignoring the 3.x timeline) here's the CPython relase history for 2.6 and 2.7:

    2008-10-01 22:05 +0000 v2.6
    2008-12-04 02:59 +0000 v2.6.1
    2009-04-14 13:16 +0000 v2.6.2
    2009-10-01 23:39 +0000 v2.6.3
    2009-10-26 01:48 +0000 v2.6.4
    2010-03-18 22:14 +0000 v2.6.5
    2010-07-03 13:57 +0000 v2.7
    2010-08-23 23:37 +0000 v2.6.6
    2010-11-27 14:40 +0000 v2.7.1
    2011-06-11 09:50 -0500 v2.7.2
    2012-04-09 19:04 -0400 v2.7.3
    2012-04-10 10:59 -0400 v2.6.8

(yeah I know it's missing the 2.6.7 tag, not sure why it's not in the repo, it should be right before 2.7.2, on 2011-06-03; also the last 2.5 release — 2.5.6 — happened between 2.7.1 and 2.7.2, 2011-05-28)