From Can They Hear You Now at Slate.com:

The Federal Communications Committee and the Justice Department are at loggerheads over a new problem in the war on terror: how to listen in on Internet phone calls. Thanks to the blistering growth of VoIP—Voice over Internet Protocol—services, which have been adopted by approximately 10 million people worldwide so far, law enforcement officials now worry that wiretapping may one day become technically obsolete. If traditional phone lines go the way of the horse and carriage, will the FBI still be able to listen in on Internet phone calls? How would it go about tapping one? Is it even possible?

After some highly technical descriptions, the article continues:

Last Thursday the FCC held an open hearing on the future of VoIP telecommunications. In a 4-1 decision, FCC commissioners, supported by Chairman Michael Powell, voted that a VoIP provider called Free World Dialup should not be subject to the same regulations as traditional phone companies—including the particulars of CALEA compliance. Instead, the FCC decided to put off the issue, stating that it would initiate a proceeding "to address the technical issues associated with law-enforcement access to Internet-enabled service" and "identify the wiretapping capabilities required." One commissioner, Michael J. Copps strongly dissented, calling the postponement "reckless."

Bottom line: The technology is growing so fast, the Government may not be able to implement monitoring internet calls even if it is allowed to do so--companies, particularly those overseas, are finding ways to free us.