I wonder if that involves something like collecting the data and storing it locally on your computer, then only sending the data once you log into facebook...
I was thinking more along the lines of a local store, but then you'd need a little script embedded into every page to handle the storage.
Essentially, instead of FB like widget -> request to facebook I would think FB like widget -> add to local datastore.
Then FB could do an optimised/aggragated query on the local database. The only thing would be that it would introduce large latency in the resulting data if its sent back only on FB login.