With that said, here are some breadcrumb schemes that I believe should be core:
*) Based on path. I have page/subpage/pagethird and the breadcrumb should read "link to page" >> "link to page/subpage" >> "title of page/subpage/pagethird". Or without the title. Remember, there is no one solution that fits all. *) Based on tags. Vocabulary name >> Hierarchy of tags provided it's a single hiearchy. Here, if you want you can provide multiple very easily, even ordering is not a problem, vocabularies have weights already.
A path could be either a set of similar url aliases, or a menu hierarchy. So "Based on path" can be divided, adding a third possibility: * Based on a menu hierarchy * Based on url aliases, regardless of their position in the menu (router, dispatch?) system. Zohar