I'm currently modifying Semantic Drilldown to be able to use the new table structure in SMW 1.2, and it looks like the structure is fairly complete - the only additional thing it would be nice to see would be a field called something like "smw_sortkey" in the "smw_insts2" table, holding the sort key that MediaWiki uses when displaying pages in a category. This field could even potentially be used by any future "instance of" special properties, since you could argue that every page representing a class should be able to list its own members in a logical order.