  Final state radiation (FSR) in pion--pair production cannot be calculated
reliably because of the composite structure of the pions. However, FSR
corrections have to be taken into account for a precise evaluation of the
hadronic contribution to g-2 of the muon. The role of FSR in both energy scan
and radiative return experiments is discussed. It is shown how FSR influences
the pion form factor extraction from experimental data and, as a consequence,
the evaluation of a_mu^had. In fact the O(alpha) FSR corrections should be
included to reach the precision we are aiming at. We argue that for an
extraction of the desired FSR--inclusive cross section sigma^(gamma)_had a
photon--inclusive scan measurement of the ``e+e- to pi+pi- + photons'' cross
section is needed. For exclusive scan and radiative return measurements in
contrast we have to rely on ad hoc FSR models if we want to obtain either
sigma^(gamma)_had or the FSR--exclusive cross section sigma^(0)_had. We thus
advocate to consider seriously precise photon--inclusive energy scan
measurements at present and future low energy e+e- facilities. Then together
with radiative return measurements from DAFNE and BABAR and forthcoming scan
measurements at VEPP-2000 we have a good chance to substantially improve the
evaluation of a_mu^had in the future.
