I like the idea of starting a Politics Open Thread if it means I won't see any more political comments elsewhere on LW.
It won't. Instead, what will happen is that people will start attaching the mental labels of "Blue" and "Green" to other commenters, based on encounters in such a thread, and these labels will apply everywhere, and consequently distort the discussions and the voting on all topics.
I agree with thomblake that the original intent of the "Politics is the Mind-Killer" doctrine wasn't to ban politics (and even that post itself wasn't intended as official Overcoming Bias policy, just advice from Eliezer!), but I am also 100% with Raemon in endorsing the anti-politics norm that has subsequently developed.
But note that the norm itself, like most human norms, is not an absolute or rigid one, just a scale of increasing costs or penalties with increasing severity of "violations". It's always been okay to mention politics in a way that shows you "know what you're doing" (proof: I have); high-status people are allowed more leeway than the lower-status (except for the very highest-status individuals, on whom norms are often strictly enforced for symbolic reasons); etc.
Theoretically, if we really needed to discuss politics (e.g. if there were pending legislation before the U.S. Congress to regulate FAI research; if Obama had criticized Republicans by invoking LW concepts in his State of the Union speech; if Putin had promised to make cryonics mandatory for everyone in Russia; you get the idea), we could.
The problem is that the norm of the politics-ban is quite broad. Basically everything that the "Personal is Political" crowd would label political is swept in.
Not only is discussion of the latest maneuverings of Newt vs. Mitt prohibited, but discussion of democracy vs. authoritarianism, feminism, the purpose of juries, etc. are considered off limits by a vocal portion of LessWrong. I have no desire to debate whether Obama's State of the Union was good policy or good politics, but the broadness of the negative reaction excludes a lot of concepts...
Summary: I propose we somewhat relax our stance on political speech on Less Wrong.
Related: The mind-killer, Mind-killer
A recent series of posts by a well-meaning troll (example) has caused me to re-examine our "no-politics" norm. I believe there has been some unintentional creep from the original intent of Politics is the Mind-Killer. In that article, Eliezer is arguing that discussions here (actually on Overcoming Bias) should not use examples from politics in discussions that are not about politics, since they distract from the lesson. Note the final paragraph:
So, the original intent was not to ban political speech altogether, but to encourage us to come up with less-charged examples where possible. If the subject you're really talking about is politics, and it relates directly to rationality, then you should be able to post about it without getting downvotes strictly because "politics is the mind-killer".
It could be that this drift is less of a community norm than I perceive, and there are just a few folks (myself included) that have taken the original message too far. If so, consider this a message just to those folks such as myself.
Of course, politics would still be off-topic in the comment threads of most posts. There should probably be a special open thread (or another forum) to which drive-by political activists can be directed, instead of simply saying "We don't talk about politics here".
David_Gerard makes a similar point here (though FWIW, I came up with this title independently).