[rwolf]

Not how cookies work. Visit any page with loads the facebook like widget iframe/img/script -> make a request to facebook with your cookie.

[jurjenh]

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.

[pork]

That's a micro/premature optimization at facebook's scale.