they're talking about the GREEN indicator, on top of the screen (which shows the iSight camera's status), not about sleep indicator (the WHITE, rectangular thing, beside the IR receiver).
The ones on my wireless keyboard are easily visible as individual holes when the light is on from 2 feet away. I don't know if the iSight is different (not having a metal macbook), but they are probably very close to the same.
http://venturebeat.files.wordpress.com/2011/11/macbook-air-w...