  This is an update of the first version. We clarify that the main results
apply to more general smooth projective varieties X than products of elliptic
curves (briefly: X is of "abelian type", e.g. an abelian variety or a product
of curves, and the Tate conjecture holds). We also deduce the Gersten
conjecture for dvrs whose residue field is the function field of such an X. In
an appendix, we construct some functoriality for etale motivic cohomology.
Finally, some errors which were in Section 5 of the first version are
corrected.
