I've phoned and gone to visit a CM today, she only let me know she wasn't registered when specifically asked. I hadn't asked on the phone because I stupidly assumed that someone advertising in the paper would have got themselves sorted out!
I am not keen on lots of aspects of registration (EYFS etc) but I am keen on insurance, first aid and getting tax credits! So it is essential that the CM is registered.
Are you allowed to just call yourself a CM and go for it? If so, so much for making it a profession!