mhansen - 1:55 pm on Oct 18, 2011 (gmt 0)
We block indexing of all our tag and category pages... reserving the indexing for the actual article content itself. Tags and category type pages, in my opinion, are for onsite visitors, not search engine traffic... so we "noindex, follow" them.
If (using your example) "Company A" deserves a page of its own, we will write and a separate detailed page about "Company A" and allow it to be indexed to attract the search visitors, and within the content of that page, also show a list of all articles that are tagged "company-a" or categorical related articles.
I hope that all made sense.