To participate, we would add a banner to the homepage on 11 February. Sample (not final) banner can be seen on the organizing site: https://thedaywefightback.org/.
The Drupal Association, which is responsible for Drupal.org is a registered 501(c)3 nonprofit organization in the United States. We do have restrictions on political lobbying as a 501(c)3 but this kind of activity is perfectly legal for us to undertake.
As a bit of history, Angie Byron (webchick) shared some previous history for Drupal.org and advocacy issues:
https://drupal.org/node/1409306 — this was the issue to do a similar thing for SOPA, and we did not take any action.
https://drupal.org/node/1409058 — this is a thread of people complaining that we did not do anything about SOPA, while WordPress, Wikipedia, etc. did.
https://drupal.org/node/1386548 — here we did get involved in politics and divorced ourselves from GoDaddy.
We recognize that our audience is not just American, but also feel that this is an important issue. What do you think?