More about Godwin's Law …
The sheer variety of people using the Holocaust as a metaphor has had one good effect: It eliminates the ability of Holocaust deniers to plausibly claim that Holocaust histories are a conspiracy on the part of Communist Jews. They have to explain how Jews and Catholics and evangelical Protestants and Moslems are all using the same metaphor. They also have to explain how communists and liberals and conservatives and libertarians are also using the metaphor.
… and its Creationist Analogue
If we try applying this to using Creationism as a metaphor, we can see the same tendency, but it is much less developed. Until a few years ago, there were only two main Creationism metaphors (one of which was divided into two submetaphors):
Belief in central planning is similar to Creationism. (I'm inclined to take this metaphor seriouly, so I'll let others criticize it.)
Belief in human uniqueness is similar to Creationism. This usually means that we should apply standard zoological concepts such as the importance of genetics and that animal species are in danger of overpopulation. There are two ways interpreting this:
When interpreted by classical “Social Darwinists,” the importance of genetics meant that we need a society of people with the best genes possible. The danger of overpopulation meant that we had to keep the inferiors from reproducing.
When interpreted by modern liberals, the importance of genetics meant that we don't have to make an enormous effort to pass traditions down to the next generation. Crime rates, drug abuse, etc. are independent of nurture. The danger of overpopulation means that we have to keep people in general from reproducing.
In recent years (probably owing to an administration that has no objection to central planning, is not trying keep the inferior races out, and is not supportive of family planning), Creationism metaphors have become a way of all-purpose Bush bashing. I suspect Creationism metaphors will be used for an increasing variety of ever more ludicrous purposes in the future.
On the other hand, at least we'll be able to ignore the real Creationists.