Are comments considered publications The journal Science has two sections for submission, Research articles and Commentary.
http://www.sciencemag.org/site/feature/contribinfo/prep/gen_info.xhtml

Under commentary, there is a section for 'Policy Forum'.  Unlike 'Education Forum' there is nothing explicit about research related to Policy.  If one submits (not invited) a manuscript to Policy Forum, is this considered peer reviewed publication? Is there a difference in citation both in format of a citation and if it is common to cite a manuscript published in Commentary?
In general, a "Comment" is always a publication. However, your question is whether it should be listed in someone's publication list, presumably along side peer-reviewed articles. I believe the relevant criterion, as mkennedy suggests, is if the comment has itself been peer-reviewed. When yes, it can go in the regular list; if not, then it should presumably be relegated to a "additional publications" list or something of that type.