Jeff handles it through a bunch of .vuh files.
The centralized services idea has floated before, but it would be a lot of work. Maybe someday ...
I'm thinking that for now we should just adopt Jeff's patch with the caveat (IMO) that we put the parameter in the .info file, that we think of the semantics as being "can be a subsite" while in reality currently the semantics will always be glued on via the subsite_packages table.
Later, if others have the need or desire to implement more flexible semantics, split off the membership services stuff from acs-subsite, etc they can do so. Wouldn't be that hard, for instance, to later augment the site node table with a "subsite" flag via upgrade scripts (though I kinda like doing that right off if it weren't difficult, problem being Jeff already has sites runnign with his existing code).
