The WTBTS have generally not named Facebook by name , referring more vaguely to "social networking sites".
I don't think that they have yet developed a coherent strategy here - as usual they are reactive , not proactive. They seem to be sending out mixed messages - the Awake articles seem to suggest that it is ok for people to have sites as long as they are careful not to allow worldy friends to register & keep their profiles hidden. Talks at assemblies & from the CO warning of the "danger of social networks" are more hard-line - essentially giving the impression that no "mature" JW would be on Facebook. I think part of this is the general demonisation of the internet from the WTBTS that it is full of apostasy & porn.
The problem for the WTBTS is that many JWs who are in foreign lands and missionaries love Facebook because they can keep in touch. One Gilead graduate in Africa I know is one of the most enthusiastic adult Facebookers I know - I guess it helps him cope with his assignment in a 3rd World country. He has thousands of JW friends all over the world & there is a lot of interaction. Actually from a JW perspective it is really positive & a very good witness as he shares his experiences. I see many JWs who from his page have been encouraged to do more & to "serve where the need is greater".
As usual I think the WTBTS is making a big mistake in their reaction. Teenagers don't become JWs because they "love Jehovah" or enjoy the (incredibly boring) JW lifestyle. They stay because of their JW friends - essentially as a result of peer pressure & the family & JW friends they have made that makes it very difficult for them to leave. All of their friends & associates , virtually without exception , are on Facebook. The WTBTS should be trying to foster these links & encourage them.
What the WTBTS fails to realise is that even nuttier religions with even more ludricrous histories (eg Mormons ,Scientologists) realise that the way to go isn't to censure & supress open information - it is to build their own information network , as it were , point their adherents to it and provide the social support that helps their religions grow. The WTBTS should embrace the new technology , exploit it readily and use it to build up existing recruits and make new ones. At present , they are like the little boy sticking his finger in the dyke.