But regardless, I think that with a significant number of people who just troll the comments at techcrunch, any kind voting system will just be gamed anyway and in doing so, will dilute it's effectiveness.
Which is opensource and can be customized. TC isn't a toy blog, so they should hire someone to work on the feature, or use 3-rd part comment system, like Intense Debate or Disqus.
Again, my belief is simply that this is not a new problem. The word "troll" has existed since the BBS days and over the last 10 years other sites have come up with clever ways (that work) to filter the trollish comments out. I don't think any of them are perfect, but it seems a bit cynical and overstated to say "any" voting system would be gamed if other sites have managed. Even digg.