Demand Progress has started an open letter to twitter and asked its subscriber's to sign it, the letter is short and as follows:Twitter's importance as an open platform has been demonstrated time and again this year. We need you to keep fighting for and enabling freedom of expression -- not rationalize away totalitarianism as a legitimate "different idea".
While I am against any for of censorship I am also against telling Twitter how to run their business. In this case they aren't abusing employees, nature or other such things. If you (Demand Progress or anyone else) are not happy with their new terms and conditions you are always free to not use their services.
That said, after reading Twitter's Tweets still must flow post it seems almost kosher.. They claim they will attempt (that is the word I dislike) to mark censored posts as such, so to inform the user they are being censored according to their government's laws. If true it could actually somehow have a positive effect, imagine people's reaction when clearly seeing how much information is withheld from them.
I would also like to correct Demand Progress on one point, Twitter is not an "Open Platform", I cannot interact with twitter users in any way unless I create an account with Twitter. Open platforms are services that use Status.net (Like Identi.ca), Friendica, Diaspora and the like, they allow users to communicate between independent nodes and hence avoid any central policing and/or control of it's users and their personal data.
In conclusion I must add that if Twitter's new rules upsets anyone it's actually a good reminder that Twitter does not belong to its users nor is it a public service. Their terms of service clearly stipulate that users accept that Twitter reserve the right to remove any content, and all of Twitter's users have accepted those terms.