This is classic.
I, for one, am thrilled to see all of the dubs on FB. It shows that society is losing some control. People are obviously questioning some of their counsel, and if you look at their groups and pages, it's obvious that they're questioning a lot of things- I see a lot of politic pages, groups for books/movies that you know aren't acceptable (Twilight is a big one), etc...Besides the Watchtower group, there's usually no sign on their profiles that they are a JW (not that this is a huge surprise, how many of us actually owned up to the fact that we were unless we had to?). Some people I know don't have the group added, either- there's no sign that they're a JW at all.
Farkel is right- this is going to build up a lot of curiosity. The ones that weren't on FB are going to join just to check it out, and they're going to do a search and realize all of their friends are already there. I'm sure that some are going to start wondering why they're not allowed to chat and share photos with their friends...hopefully they'll start wondering why they're not allowed to do other things, too.
Then we'll welcome them here
I've read before that 2/3 of born-ins leave...I think FB will put a big dent in how many stay.