Most scientific journals begin their instructions to authors with a strong statement against prior or double publication. The New England Journal of Medicine (NEJM) states, "Manuscripts containing original material are accepted for consideration if neither the article nor any part of its essential substance, tables, or figures has been or will be published or submitted here before appearing in the Journal."
Most journals then list exceptions to the blanket rule; for example, presentation of the results at a poster session or meeting, with concurrent publication of the results in a meeting abstract. However, a number of publications are interdicting their authors from any prior publication of a paper on a personal or institutional Web site. For example, from the NEJM again: "Posting a manuscript, including its figures and tables, on a host computer to which anyone on the Internet can gain access will constitute prior publication." I...