Your mobile number available to anyone?

This looks like a genuine worry:
http://news.bbc.co.uk/1/hi/programmes/working_lunch/8091621.stm

This potentially opens the door to more SMS spam to find its way to your inbox.

This should be an opt in service rather than opt out.

You can either send a text to 118800 or do it on their website, which must be hammered as it is down:
http://www.118800.co.uk/

The Guardian seems to confirm this:
http://www.guardian.co.uk/money/2009/jul/13/mobile-phone-directory-suspended

Kon Boot illustrates why physical security still matters most

http://www.piotrbania.com/all/kon-boot/

This little utility allows modification of the Windows and LINUX kernel whilst booting to allow log on without knowing the password.