I don't know if you've heard the latest news from the MAGIC telescope researchers, but they may possibly have come across evidence of Quantum Foam: http://www.universetoday.com/2007/10/03/high-energy-gamma-rays-go-slower-than-the-speed-of-light/ Gamma rays were apparently found to have arrived 4 minutes behind other photons that were supposedly emitted at the same time from a Blazar source 500 million light-years away. This has led to some speculation that the delay may be due to the intervention/interaction of Quantum Foam. Obviously there are many possibilities for error or alternative conclusions in this measurement. But if enough credence is given to the results to warrant further investigation, then what other means could be devised to test out this hypothesis? Merely observing other blazars, or could some clever in-laboratory means be used, that would provide much more controlled and known test conditions?