Question about fast light

I came across some interesting articles about "fast light", where you can have light pass through a medium at faster than c speeds. Supposedly, this does not violate the rules of relativity because information does not travel faster than the speed of light (c).

My question is this: how do they measure if they've got light traveling faster than c? Would not the detection of this wave send the information that it traveled faster than c?

To get less esoteric, let's take this example: my mother would call her mother when she got back to her own house after a visit, just to let her know she had arrived safely. Because it was a toll call, she'd let it ring twice, then hang up. This would convey the information "I have arrived home safely". If she could hit a button that would send a light beam through a medium at faster than c, and my grandmother was equipped to detect this, would that, then, be information travling at faster than light speeds?

I hate not having Einstein around to answer these questions when they come up...