I think so too. I had been leaning in this direction since I read in the API docs that a comment is a post under the hood.
However, I would also conjecture that the Google evaluations get some tailoring through machine learning and human curation as steemit becomes more prominent (perhaps even breaking 1,000 triggered something of that sort).
Again, pure conjecture on my part —though I did briefly work as curation drone for a Google contractor, and also a long time ago at a SEO conference I heard things like that do come into play (or at least they did back then)