BT's AGM had more questions asked than usual, about their illegal operations with Phorm.
There is an excellent account on the Dephormation website.
The NODPI (No Deep Packet Inspection) website is also worth a look.
If you don't want the government opening all your letters and parcels, recording all your phone calls, and installing cameras in all your rooms, it's worth trying to stop what they are already attempting to do, as it is the thin end of a very unpleasant wedge.

