  We propose a measure of interaction-induced ground state entanglement in
many-fermion systems that is experimentally accessible. It is formulated in
terms of cross-correlations of currents through resonant fermion levels weakly
coupled to the probed system. The proposed entanglement measure vanishes in the
absence of many-body interactions and it is related to measures of occupation
number entanglement. We evaluate it for two examples of interacting electronic
nanostructures.
