It's called a Code-A-Thon. This particular Code-A-Thon is sponsored by a group called the League of Technical Voters, which aims to involve technical people in the political process. The head of this group, and the head of the Code-A-Thon, is Silona Bonewald. (She's pictured at right, from her personal Web site.) Bill Gates she's not. (For this I am thankful.)
The coders at this Code-A-Thon will concentrate on building tools for political activism. While many of the groups represented are on the liberal side of the spectrum, the code they will write has no politics. Any site using Drupal will benefit. Thus, the biggest political site on the left will gain no benefit from this Code-A-Thon. DailyKos runs Scoop.
As a point of personal disclosure, I should note I manage a Drupal site. I'm one of the beneficiaries here.
While it's not unknown for programmers in proprietary shops to work long, long hours (my dear wife is doing just that these days) all those hours are paid-for, with both motivation and direction clear and capitalistic.
That's not always true in open source. People contribute to open source for all sorts of reasons -- profit being one, altruism being another, politics being a third, learning being a fourth. Open source also draws on all these motives at all levels -- management, coding, testing, bug reporting.
Those looking for reasons behind open source productivity might want to visit Austin October 13-15. Oh, and bring your own laptop.
UPDATE: Contests are another great way toward open source productivity. WorldLabel is now sponsoring just such a contest to get more templates and clipart for OpenOffice. (Disclosure. I use OpenOffice.)