When people ask on the support board about "why do I get this message of 'cannot post as non-user', what does that mean," they are trying to post an entry or comment while logged in as a community account. Usually, they are trying to post to "goats_r_cool" while logged in as that same community.
Communities, as stated in FAQ 77 - "What is a community?", cannot post entries/comments. The user needs to be logged in as something else (the maintainer account, another journal with posting access) in order to post things.
I'd like to suggest that something to that effect be added to the "How do I post?" FAQ. It would seem to fit in that FAQ nicely, and is probably the first place the user would look (if they, you know, used the FAQs for themselves...), rather than the "What is a community" FAQ.
So, perhaps this sentence (or similar) added to the end of the first paragraph:
"Please note that community accounts do not have posting rights. Communities cannot post entries or comments in any other journal or community, including themselves."
OK, that wording is not so good, LOL, but that's the gist of it--can't post entries or comments to anywhere, including the community account itself.
Thoughts? Better suggested wordings?