  The B modes generated by the lensing of CMB polarization are a primary target
for the upcoming generation of experiments and can potentially constrain
quantities such as the neutrino mass and dark energy equation of state. The net
sample variance on the small scale B modes out to l=2000 exceeds Gaussian
expectations by a factor of 10 reflecting the variance of the larger scale
lenses that generate them. It manifests itself as highly correlated band powers
with correlation coefficients approaching 70% for wide bands of Delta l/l
\~0.25. It will double the total variance for experiments that achieve a
sensitivity of approximately 4 uK-arcmin and a beam of several arcminutes or
better. This non-Gaussianity must be taken into account in the analysis of
experiments that go beyond first detection.
