A CAM "Conditional Access Module" in laymans terms is a decoder, the unit into which the viewing card is placed. There is a different CAM for each encryption method, but some CAMs can be flash programmed to operate across two or three encryption types.
There is not a CAM available for Sky as yet and the encryption system Videoguard has not been hacked, although you are likely to hear almost daily that a friend of a friend knows someone who has seen a working pirate card.
Apparently, Videoguard CAMs are in development and will be available soon in Italy, where Videoguard is also used. Indeed, this is nessessary to comply with an EU directive requiring all encryption systems used in the EU to be available in the form of CAMs for use with a standard receiver. However, Sky is not famous for taking the blindest bit of notice of EU directives where these would affect Sky's Total Control of the hardware used to receive it. We can thereore expect that Sky will put in place some devious means of preventing Sky (or BBC) cards from working in digital receivers fitted with Videoguard CAMs.