Black ravens and red herrings

Yup, the "update based on the magnitude of your surprise" heuristic matches this pretty well.  

Does an observation of a black herring or black apple reduce the claim of all ravens are black -- or somehow be less forceful a failure to disprove the claim? What about a blackberry?

I don't think what you're saying makes sense in general. For one thing, you're assuming (as does the model in the post) that non-ravens being black is anti-correlated with all ravens being black. Maybe more interestingly, you're assuming something about the process that presented you with a green apple. If the process is "look for a non-black object", then yeah, we've probably gotten evidence in favor of all ravens are black--this corresponds to "trying and failing to disprove the hypothesis". If the process is "look for a non-raven object" or just "look for an object", then we've probably gotten very little evidence about ravens, and the direction of the evidence depends on our prior.

It is indeed evidence proof that all ravens are black, as well as that all ravens are white, and also that no ravens exist. These are not mutually contradictory propositions.

Of course, it is also proof that you are a green apple. (User name checks out?)

nit:

and find no non-white ravens (but do find black ravens)

I think you meant "no non-black ravens" here.

Nice! I. J. Good himself pointed to another example of how this rule might break in his paper appropriately titled (for my post anyway), "The White Shoe is a Red Herring",

Suppose that we know we are in one or other of two worlds, and the hypothesis, H, under consideration is that all the ravens in our world are black. We know in advance that in one world there are a hundred black ravens, no non-black ravens, and a million other birds; and that in the other world there are a thousand black ravens, one white raven, and a million other birds. A bird is selected equiprobably at random from all the birds in our world. It turns out to be a black raven. This is strong evidence (a Bayes-Jefrreys-Turing factor of about 10) that we are in the second world, wherein not all ravens are black.

From Wikipedia,

Hempel rejected this as a solution to the paradox, insisting that the proposition 'c is a raven and is black' must be considered "by itself and without reference to any other information", and pointing out that it "... was emphasized in section 5.2(b) of my article in Mind ... that the very appearance of paradoxicality in cases like that of the white shoe results in part from a failure to observe this maxim."

ETA: I now see that the paper you linked cites this example. Cool.

More than the prior, I find the sampling process to be nonsensical. Why would we expect to run across the objects in the world uniformly at random? Seeing ravens is highly correlated with being outside, looking at the sky, etc, so why wouldn't seeing white ravens have similar but much narrower requirements, like being on a specific island? Adding something along these lines to our model should make the bayesian evidence gained by observing either black ravens or non-black non-ravens quickly go to 0.

To address the paradox: If I show you a box and (trustworthily) tell you that there's one object in the box, and then you look through a tiny hole in the box so all you can see is the color, and you see not-black, that is probably evidence that not all ravens are black (unless we think there's way more non-black objects in worlds where all ravens are black, enough to overcome the possibility that we're looking at a non-black raven). Then, if we open the box and see a non-raven, that observation is evidence in favor of "all ravens are black", because we've (mostly) screened off the evidence against--we definitely weren't looking at a nonblack raven.