[zombees]

In this case, what they mean is that the signal will be truly line of light. As you go up in frequency, radio starts to behave more like light so while you may get some convenient reflections here and there, for the vast majority of the time, if the antenna doesn't have a clear path to the transceiver, you won't know there even is an access point.

[digi_owl]

I suspect this can be quite convenient for various places where you want to limit access to individual rooms etc, but don't want to deal with the tangle of cables and ports that a wired network would require.