My subjective impressions: predictors very rarely quote or reference each other when making predictions. Many predictions seem purely an individual guess. I've seen no sign of an expert consensus, or of much experts critiquing or commending each other's work. I really feel that predicting AI has not been seen as something where anyone should listen to other people's opinions.

They may not cite each other, but the influence can still be there as background reading etc. I may not cite Legge when I think there's a good chance of breakthroughs in the 2020s but the influence is there (well, it was until I mentioned him just now). To give a real-world example, compiling http://www.gwern.net/2012%20election%20predictions I know that the forecasters were all reading each others' blogs or twitters etc because in scouring their sites I see enough cross-links or similar topics, but anyone who looked at just the relevant pages of predictions or prediction CSVs would miss that completely and think they were deriving their similar predictions from independent models.

I think there's a lot of shared ideas and reading which rarely is explicitly cited in the same passage as a specific prediction with the exception of really offensive estimates like Kurzweil's self-promoting (have you been reading the reviews of his latest book? Everyone's dragging out Hofstadter's old dog shit quote, which one can't help but feel that he would not have been so explicit and crude if Kurzweil didn't really rub him the wrong way). But I don't know how one would test the consensus idea other than waiting and seeing whether expert predictions continue to cluster around 2040 even as we hit 2020s and 2030s.