Given that a lot of client devices being just a single antenna, surely there won't be too much uplink beam forming happening though. Even more so when MU-MIMO comes in, which is a downlink feature.
I would think that given the smart antennas actually add directionality to the signal it would be a preferred option over beam forming (which uses phase shifts to get constructive interference of the wave forms at the client location) - or maybe a combination of both would be the best solution?
Beamforming and smart antennas are not mutually exclusive so you can use both, which is what Ruckus has done for quite awhile and Aruba now does with some models. It would cetainly be interesting to see if Aerohive is looking at using any smart antenna technology in their future access points.