I think AGI before human uploads is far more likely. If you have hardware capable of running an upload, the trial-and-error approach to AGI will be a lot easier (in the form of computationally expensive experiments). Also, it is going to be hard to emulate a human brain without knowing how it works (neurons are very complex structures and it is not obvious which component processes need to appear in the emulation), and as you approach that level of knowledge, trial-and-error again becomes easier, in the form of de novo AI inspired by knowledge of how the human brain works.

Maybe you could do a coarse-grained emulation of a living brain by high-resolution fMRI-style sampling, followed by emulation of the individual voxels on the basis of those measurements. You'd be trying to bypass the molecular and cellular complexities, by focusing on the computational behavior of brain microregions. There would still be potential for leakage of discoveries made in this way into the AGI R&D world before a complete human upload was carried out, but maybe this method closes the gap a little.

I can imagine upload of simple nonhuman nervous systems playing a role in the path to AGI, though I don't think it's at all necessary - again, if you have hardware capable of running a human upload, you can carry out computational experiments in de novo AI which are currently expensive or impossible. I can also see IA (intelligence augmentation) of human beings through neurohacks, computer-brain interfaces, and sophisticated versions of ordinary (noninvasive) interfaces. I'd rate a Singularity initiated by that sort of IA as considerably more likely than one arising from uploads, unless they're nondestructive low-resolution MRI-produced uploads. Emulating a whole adult human brain is not just an advanced technological action, it's a rather specialized one, and I expect the capacity to do so to coincide with the capacity to do IA and AI in a variety of other forms, and for superhuman intelligence to arise first on that front.

To sum up, I think the contenders in the race to produce superintelligence are trial-and-error AGI, theory-driven AGI, and cognitive neuroscience. IA becomes a contender only when cognitive neuroscience advances enough that you know what you're doing with these neurohacks and would-be enhancements. And uploads are a bit of a parlor trick that's just not in the running, unless it's accomplished via modeling the brain as a network of finite-state-machine microregions to be inferred from high-resolution fMRI. :-)

How valuable is trying to shape the two probability distributions themselves? Should we be devoting resources to encouraging people to do research in computational neuroscience instead of AGI?

It's an interesting methodology, but the Maes-Garreau data is just terrible quality. For every person I know on that list, the attached point estimate is misleading to grossly misleading. For instance, it gives Nick Bostrom as predicting a Singularity in 2004, when Bostrom actually gives a broad probability distribution over the 21st century, with much probability mass beyond it as well. 2004 is in no way a good representative statistic of that distribution, and someone who had read his papers on the subject or emailed him could easily find that out. The Yudkowsky number was the low end of a range (if I say that between 100 and 500 people were at an event, that's not the same thing as an estimate of 100 people!), and subsequently disavowed in favor of a broader probability distribution regardless. Marvin Minsky is listed as predicting 2070, when he has also given an estimate of most likely "5 to 500" years, and this treatment is inconsistent with the treatment of the previous two estimates. Robin Hanson's name is spelled incorrectly, and the figure beside his name is grossly unrepresentative of his writing on the subject (available for free on his website for the 'researcher' to look at). The listing for Kurzweil gives 2045, which is when Kurzweil expects a Singularity, as he defines it (meaning just an arbitrary benchmark for total computing power), but in his books he suggests that human brain emulation and life extension technology will be available in the previous decade, which would be the "living long enough to live a lot longer" break-even point if he were right about that.

I'm not sure about the others on that list, but given the quality of the observed date, I don't place much faith in the dataset as a whole. It also seems strangely sparse: where is Turing, or I.J. Good? Dan Dennett, Stephen Hawking, Richard Dawkins, Doug Hofstadter, Martin Rees, and many other luminaries are on record in predicting the eventual creation of superintelligent AI with long time-scales well after their actuarially predicted deaths. I think this search failed to pick up anyone using equivalent language in place of the term 'Singularity,' and was skewed as a result. Also, people who think that a technological singularity or the like will probably not occur for over 100 years are less likely to think it an important issue to talk about right now, and so are less likely to appear in a group selected by looking for attention-grabbing pronouncements.

A serious attempt at this analysis would aim at the following:

1) Not using point estimates, which can't do justice to a probability distribution. Give a survey that lets people assign their probability mass to different periods, or at least specifically ask for an interval, e.g. 80% confidence that an intelligence explosion will have begun/been completed after X but before Y.

2) Emailing the survey to living people to get their actual estimates.

3) Surveying a group identified via some other criterion (like knowledge of AI, note that participants at the AI@50 conference were electronically surveyed on timelines to human-level AI) to reduce selection effects.

It surprises me sometimes that no one else on LW/OB seems to've heard of Kelly's Maes-Garreau Point.

It would be very surprising if you are right. I expect most of the people who have thought about the question of how such estimates could be biased would think of this idea within the first several minutes (even if without experimental data).

Kelly doesn't give references for the dates he cites as predictions for the singularity. Did Eliezer really predict at some point that the singularity would occur in 2005? That sounds unlikely to me.