As far as I can figure out, it's simply another page on Facebook. And apparently, I've criticised it.
I wasn't quite aware that I had, but there you go. The Times says so, so it must be true. http://www.timesonline.co.uk/tol/news/uk/article4057686.ece 
No doubt we will learn more of the scope and dynamic of the venture shortly. It's done a good job with the publicity, though.
The slightly curious story is here: http://tinyurl.com/6m82ak 
Dave Walker has his own angle on the Church Times : http://www.churchtimes.co.uk/blog_post.asp?id=57569 
Incidentally, a number of people have been having difficulty finding 'Faithbook', or distinguishing it from other social networking and web pages that use the same name. The Daily Telegraph has a helpful guide at the end of its report: http://tinyurl.com/5z69ak