No, it is not about knowledge, it's about belief (or any other representational state). An externalist believes that the content of a belief -- what a belief is about -- is determined by causal entanglements with the environment. I have beliefs about Eliezer Yudkowsky because my brain states are causally entangled with Eliezer Yudkowsky. These beliefs need not qualify as knowledge. Say a physical duplicate of me appeared on Mars by a random thermal fluctuation. Even though that duplicate has the same brain state as I do, his brain state is not causally entangled with Eliezer, so the externalist would say that he does not have beliefs about Eliezer. If you think this is obviously false, you are most likely an internalist.
keyword "about".
Despite being (IMO) a philosophy blog, many Less Wrongers tend to disparage mainstream philosophy and emphasize the divergence between our beliefs and theirs. But, how different are we really? My intention with this post is to quantify this difference.
The questions I will post as comments to this article are from the 2009 PhilPapers Survey. If you answer "other" on any of the questions, then please reply to that comment in order to elaborate your answer. Later, I'll post another article comparing the answers I obtain from Less Wrongers with those given by the professional philosophers. This should give us some indication about the differences in belief between Less Wrong and mainstream philosophy.
Glossary
analytic-synthetic distinction, A-theory and B-theory, atheism, compatibilism, consequentialism, contextualism, correspondence theory of truth, deontology, egalitarianism, empiricism, Humeanism, libertarianism, mental content externalism, moral realism, moral motivation internalism and externalism, naturalism, nominalism, Newcomb's problem, physicalism, Platonism, rationalism, relativism, scientific realism, trolley problem, theism, virtue ethics
Note
Thanks pragmatist, for attaching short (mostly accurate) descriptions of the philosophical positions under the poll comments.
Post Script
The polls stopped rendering correctly after the migration to LW 2.0, but the raw data can be found in this repo.