German researcher Karsten Nohl has cracked the encryption used for GSM. His team has made information and tools needed to replicate the attack with a somewhat modest set up. The A5/1’s 64-bit encryption key used in GSM is simply too short for the kind of computing power widely available today. Considering that the technology is over 20 years old, however, it’s robustness is still remarkable. Here’s the A5/1 Cracking Project’s website.