Personal wikis are a source for endless fascination, and they would lend themselves towards machine learning to the extent that you can imagine personal information management as a machine-assisted process. These are as individualized as snowflakes and about as durable.
Public utility wikis come in a variety of flavors, and don't always share an equivalent management structure or function. Sometimes there is a very small team of creators and a large periphery of consumers, and it's possible for a suitably designed personal effort to extend to public use if approached with care. Arborwiki fits the bill for this for me; I've made a lot
of edits there, but the most popular pages have the most diverse edit base.
Team wikis appear in this decade to be embedded in some other bigger system that needs a shared editable place but that also has some other explicitly transactional work going on. Wiki nature does not include the verbs "assign", "delegate", "report on", or even really "decide", and if you are doing any kind of process work you often land on something beyond a
simple "edit this page".