Great -- I'm hoping L1-regularized logistic regression will become the standard first thing to try in these quick-n-dirty "predict response variable from text" experiments. That's our approach too. (I assume this is L1 or similar since you mention regularization causing feature selection.)
[[ Edit: deleted question about what 'k' is for the discretized 1{ rank <= k } response. It's mentioned in the article ]]
[[ Edit: deleted question about what 'k' is for the discretized 1{ rank <= k } response. It's mentioned in the article ]]