And this week along a stretch of border in Arizona, the government is bringing online a test of a high-tech virtual fence.

NPR: Immigration Stalemate Frustrates Arizona

Mr. McCaul says the bungled project called SBInet, which included the virtual fence plan, set back the cause of border security five years.

WSJ: Border-Security Drone Program Off to Rough Start

Tests of the virtual fence didn't lead to nearly as many arrests as designers had hoped, and the lag from sensor detection to transmission of an image to border agents was apparently a big part of the problem.

ENGADGET: Border Patrol's virtual fence canceled for not being as good as a fence

If I were president of the United States, I could do something about that by deploying a fence, by deploying a virtual fence, by having a BorderStat system like my COMSTAT system that brought down crime in New York, and just stopping people from coming in, and then having a tamper-proof ID card.

CNN: Giuliani's responses at the CNN/YouTube debate

No other virtual currency will even come close to that kind of vibrant liquidity and building walls to ring fence a virtual environment will turn out to be a counter-productive strategy.

FORBES: Virtual Currencies and Roach Motels