This is a definition I came across on a US site IMedia Connection.

SEO PR is a buzzword that is both over-hyped and under-hyped at the same time. You see, while SEO PR is currently in buzz overkill mode in the search engine marketing (SEM) industry, it is drastically underutilized in the traditional PR world.

I think it sums things up fairly well, except this side of the pond there's a lack of over-hype