The BBer has not been active for over 18months now, she stopped coming on at a very very hard time in her life. It ewally just shocked me that I realised who it was. If I was ever to say anything to her I think I would actually leave BB out of it and it would only be about her blog anyway. Still I don't know.
I would go from the blog angle rather than the BB angle. She may bring up BB herself and you could decide whether to mention it or not, it sounds like she left after very difficult personal circumstances, so I think you are right not to mention the BB connection unless she brings it up hersefl. It is easy to find a blogger on Google/Internet as they quite often have pictures up of themselves, it's not as common to find another BB'er.