In one of the monthly updates(I think it was April) G supposedly limited multiple same domain results. That was a total BS. My website fills the first 4 pages for a three word keyphrase (think blue widget picture). It's just that those widgets come blue but no one posts a picture of them somehow. But 4 pages? Anyway I see almost no traffic from that keyphrase, so I guess that's why G doesn't pay attention to that particular search.