[bandushrew]

Dude, if I am a facebook user who has not logged out, they can send cookies as much as they like.

The browser manages this - if they are logged in, set a cookie that will be sent to the hypothetical 'like' subdomain of facebook, if they are logged out, remove the cookie.

This kind of functionality is really not rocket science, there are dozens of ways to implement it and I feel kind of stupid talking about it.

There are reasons for facebook not doing this, but they are not technical ones.