I'd recommend you do a Custom Search starting from 2/18/13, the date Posthaven was announced, in order to do a fair apples-to-apples comparison. The results are much different. :)
Although app.net has the advantage of time, including the launch hype about Posthaven but not app.net is quite unfair :)
Anyway, I think number of Google results is a bad measure, since it counts posts and comments equally, and seems somewhat arbitrary in its choice of comments.