GSM Voice Call Interception on the Cheap?

Is it possible to intercept GSM voice calls (AT&T and T-Mobile in the U.S.) using $1500 worth of hardware and free Open Source software. That’s what Reuters reports security researcher Chris Paget is discussing with other security experts at the Defcon conference in Las Vegas this week.
Hackers to get eavesdropping lessons on cell calls
It has been long known that GSM, designed in simpler times, is not secure in the world of today. What is new about Chris Paget’s technique is the reported ease and relatively inexpensive hardware required to make the crack.
If you are interested in a clear detailed discussion on this topic, I recommend referring to Security Now podcast 213 recorded on September 8, 2009. Cyber-security expert Steve Gibson, who provides weekly lessons in security, provides the information in a way most people can understand.
Security Now 213: Cracking GSM