[fyrabanks]

That first technique A) is very audibly noticeable B) requires you to put the laptop on a chair and wheel it around the room to make up for the fact that you only have a single microphone.

The second technique basically only understands gestures.

I wouldn't be at all worried about this in the wild...

[s_q_b]

Someone actually did it to China's PLA Unit 61398 using a technique similar to this: http://www.gizmag.com/microphone-room-mapping-epfl/27985/, so I'd say it's worth worrying about in the wild.