> One such piece of magic new to 802.11n Wi-Fi is called "beamfoming"
That's not quite true. 802.1ln has MIMO (Multiple-Input Multiple-Output) processing, with "multiple" referring to the number of receiver and transmitter antennas. Beamforming is a special case of MIMO, and MIMO is a generalisation of beamforming.
In a "Line-of-Sight" channel with no reflectors, MIMO converges to a beamforming solution. Capacity is then limited by the ability for the rx/tx array to resolve each antenna in the tx/rz array: the diffraction limit.
In a "rich" channel, with reflectors, MIMO converges to a more complex solution, which takes advantage of the angular separation of the reflectors to resolve the individual rx/tx antennas, even if they are too close to each other to resolve with beamforming. Yes, counterintuitively MIMO capacity goes up as the channel become more complex/rich and less line-of-sight, whereas with just beamforming the capacity would typically go down.
You can sort of think of MIMO as being beamforming where beams are bouncing off widely spaced reflectors, but even that doesn't do it justice. In reality, each "beam" is replaced with complex wavefront ("mode") which is matched to the environment and each mode is orthogonal to the other.