[Aliese]

You will see any/all friends who are online on your list regardless of which servers they're on, but you'll have to be on the same one to play together/crew up.

ETA: I would also kind of like to see which server someone's on (though, that'd be another feature I'd want to be able to disable if I want to play alone). The best you can do now is click on names and see if the crew option highlights...