At the url http://en.wikipedia.org/w/api.php?action=parse&page={page_name} you get the html content and some metadata of a Wikipedia page.
E.g. Richard D. James Album

With parameters prop=text&format=json&callback=mycallback you get only the html text with jsonp format.
E.g. Richard D. James Album

With parameter section=0 you get just the infobox and the abstract of the page.
E.g. Richard D. James Album

With parameter prop=text|images you get also the images names.
E.g. Richard D. James Album

To get the full path of the images follow these guidelines: http://commons.wikimedia.org/wiki/FAQ#What_are_the_strangely_named_components_in_file_paths.3F