We derive a simple analytic expression for q \bar{q}, g g -> t \bar{t} -> b
W^+ \bar{b} W^- -> b \bar{l} \nu_l \bar{b} l' \bar{\nu_{l'}} for on shell
intermediate states with the interference effects due to the polarizations of
the t and \bar{t}. We then investigate how this effect may be measured at
Tevatron or other hadronic colliders