Hard to image such a bullet can be achieved even with current
Nano technology. Given that a bullet does not have any propulsion
system plus it practically relies on the kinetic energy generated
at the ignition of the gun power, while it doesn't have any
aerodynamic "wings" to change course and direction, I can't see how
the above can be achieved.
However, I would suggest that a new electronically fired infantry
weapon could be developed in the future where the future bullets
will have miniture IR seeker and deploy "wings" to do minor flight
adjustments. The weapon will have a IR imager that locks onto the
target, pass the target and environmental information (distance,
temperature, humidity, IR signature strength, etc) to the bullet
before being fired. The fired bullet will do all the necessary
calculation and necessary flight adjustment and guide its remaining
energy to the target. Of course the cavet is that the flight
adjustment won't be big, thus, the original target position cannot
be too far off from the initial calculated point.
Alternatively, if the weapon is size up to fire a bullet that
contains minitual propulsion system, then we have an assault weapon
like the one they used in the movie "The Fifth element" where the
bullet will wizz towards the target... too sci fi for me
though.
Anyway, this is going towards a tangent from the initial
discussion... 
