I wonder how he learned Luke's Full name... I don't remember it being mentioned in ANH... in fact... save for about 10 seconds of Leia screaming "Luke it's too late!" as he kicked some old man clothes on the floor, he never heard the boys name lol...

Leia: "Aren't you a little short for a stormtrooper?"

Luke: "Huh? Oh the uniform! I'm Luke Skywalker. I'm here to rescue you."

Now that the old Emperor dialogue has been changed, this is the only time you hear his entire name in the whole trilogy.

I think he was saying the Death Star hangar scene was the only time Vader had a chance to hear Luke's name, first or last, in A New Hope.

And doesn't Luke say his full name in his message to Jabba in ROTJ? I think Bib Fortuna says it too.

In any event, I agree that in the time between films, Vader, the Emperor, and pretty much the whole galaxy would have heard Luke's name - blowing up the Death Star would surely make him famous...