Similarly, Hacker News homepage might be considered spam because it's mostly titles of articles. Until you take into account the value of the votes--which is value that these google guidelines don't address clearly.
For example, links such as http://topsy.com/s/toyota+grand+jury+subpoena are submitted into google to be indexed.
This is a bummer as this just serves to increase the noise to the detriment of getting good results.
I don't think Google's search results or even Hacker News really ever shows up too often on SERPs except for their respective brands... so it doesn't really apply. They are destination websites not focused on search traffic.
I don't think so. It looks like the policy is in place to keep you from having to perform multiple clicks to get where you want. In the common use case (I visit Google.com, type a search, get a result) I do not have to click on anything more than the search result to get where I am going. The difference is in a use case where my search result takes me to a search results page, which means I am only halfway (or less) to my target page after clicking on the Google search result. This doesn't mean, necessarily that all Mahalo content is bad, but that Google shouldn't be indexing Mahalo search results pages, and instead should link directly to the resultant content pages instead (scraped or not.)
Similarly, Hacker News articles should not be the result of a search done on the news title (as HN's link to the original article actually increases the article's score, right?), but should perform better if the matched term is found in the HN-specific content (e.g., the commentary we create on HN only.)
I'm sure that there are (hopefully) edge cases in which a search for the article title returns the HN link instead of to the original article, but that should be the exception to the rule. Of course, if HN were to have an absurdly high page rank and link to a relatively unknown (or new) blog, it would likely lead to a result on here, instead of the other way 'round.