This may be old news to some, but just in case... I got what I thought was one of the circular spam mails claiming that next week there will be a directory of mobile phone numbers launched and that people had to opt out PDQ should they want to. Did some checking on it and found (not least on BBC 4's site) that it appears to be true.
Don't know about you, but I like the peace of not having a landline and so not getting disturbed by fatuous idiots, I also screen any calls on my mobile before answering, but I don't really want it going off with monotonous regularity - only the chosen few get my number and that's how I like it.