It’s probably more useful to look at the VK and Facebook integrations for examples, as they are more featureful.
Socialcache can handle different types of data, like “Posts”, “Contacts”, “Notifications” or “Images”, and Buteo can do different types of “sync” via its plugins, some of which intersect with the Socialcache types (e.g. “Notifications”, “Posts”, “Images” are in both, but “Backup” or “Calendar” is only in Buteo). (And in addition we have Accounts, which have service profiles, including “posts” and “microblogging” 
).
There was a News article talking about Buteo in more detail, maybe that’s useful. It has a nice picture at least: