The interest of wikisource project for a formal and standardyzed set of book metadata (I presume from Dublin Core) into a database table is obviuos. Some preliminary tests into it.source suggest that templates and Labeled Section Transclusion extension could have a role as "existing wikitext conteiners for semantized variables"; the latter perhaps more interesting than the former one, since their content can be accessed directly from any page
I'd like that book metadata would be considered from the beginning of this interesting project.
Alex