Here is a hugely popular article on LinuxSecurity.com from 2007 that is even more true today.

Two Cambridge researchers have devised a relay attack with a hacked chip and PIN terminal that could enable attackers to bypass bank card security measures.

Saar Drimer and Steven Murdoch, members of the Cambridge University Computer Laboratory, demonstrated in January how they could modify a supposedly tamper-proof chip and PIN terminal to play Tetris. They have now extended the hack to demonstrate how they can compromise the system by relaying card information between a fake card and a genuine one.

Chip and PIN, introduced last year, is a security measure in which a customer must enter a four-digit code when they use a credit or debit card. The researchers argue that the system is not as secure as the banking industry claims.

Details of the prototype attack were released on Monday. In it, Drimer and Murdoch demonstrate how a chip and PIN system could be compromised to steal diamonds.

The link for this article located at ZDNet UK is no longer available.