[monotreme]

I have my vb set up as a subdirectory. program files in the same domain can get the vb cookies in this setup. assuming that you don't have them set to something odd. In vb I have them just covering the whole domain and the cookie path is the default /

If the user has a persistent login, then the bbuserid and bbpassword cookies exist and my outside script can get them.

a simple print_r($_COOKIE) will confirm this for you. I don't understand your questin
"how do I read it?" What you said: $_COOKIE['bbuserid'] -- that is how you access it, if it exists.

If the user is logged into vb but not a "rememberme" there are no external login cookies available.

So I'm supposeing that vbulletin is maintianing session only login in it's database. To get that your script would have to open a connection to the vb db and read the session table.