In installed it. It said only five people on my friends list had it and none of those are people I would actually talk to on the phone. I guess both people have to have it for it to work.
That is what I got from it too. I have a bunch of FB friends, but most of my family and friends don't have a droid. My brother has an AG Ally and his on FB so I'll try and give it a whirl with him this weekend.