  General interest in a precise determination of the threshold pi-pi amplitudes
has recently increased markedly due to a controversy regarding the size of
<0|qbar q|0>, the scalar quark condensate. This paper examines the current
experimental information on the pi-pi scattering lengths, in particular the
recent low energy pi N -> pi pi N data from several laboratories and the
related application of the Chew-Low-Goebel technique well below 1 GeV/c
momentum. It appears that uncertainties related to the treatment of
non-pion-exchange backgrounds in these studies do not yet allow an unambiguous
resolution of the <0|qbar q|0> size. However, near-term prospects for new
model-independent results of improved precision are very good.
