It really depends on what the powers-that-be intend for T.M.O to become. If it's to be a general Maemo/Nxx0 user site, i think more "checks and balances" need to be implemented for the forum to prevent unproductive chaos and low s/n.

Rather than a one-strike idea as you suggest, i would prefer something that would be both incremental and cumulative:
-No Thanks would subtract one from the Thanks count
-A filter that could hide individual posts below some threshold
-A filter that could hide all posts by a person below some threshold

This is not only great for allowing community-balanced moderation, it lets people choose the volume of talk they want to see.

I just realized that i've largely described slashdot. Horrors. Don't let that distract you from the good points, though.

Edit: i have to say that for the first time in my life i have added entries to my block list. I come here mostly for informative discussion so i guess my tolerance of useless and acerbic chatter is lower than usual. If i feel that way, i'm sure there are many others who would like to see this problem nipped in the bud.