Oh?
Elaborate.
http://en.wikipedia.org/wiki/Gravitational_wave_detector
Do they work in free-fall?
Yes. From the article:
"Space-based interferometers, such as LISA and DECIGO, are also being developed. LISA's design calls for three test masses forming an equilateral triangle, with lasers from each spacecraft to each other spacecraft forming two independent interferometers."
That looks more like a description of what they are trying to do, not whats been done.
But tell me, are they using interferometers to detect gravity? (ie, using the affects of gravity on photons)
From what you posted, it looks like they are.