From the FAA:
"POLARIZATION. Polarized lenses are not recommended
for use in the aviation environment. While useful for blocking
reflected light from horizontal surfaces such as water or
snow, polarization can reduce or eliminate the visibility of
instruments that incorporate anti-glare filters. Polarized lenses
may also interfere with visibility through an aircraft windscreen
by enhancing striations in laminated materials and mask the
sparkle of light that reflects off shiny surfaces such as another
aircraft?s wing or windscreen, which can reduce the time a pilot
has to react in a ?see-and-avoid? traffic situation."
From the Aviation Safety Letter (Canada):
"Polarized lenses are
great for fishing, but bad for flying. Due to
manufacturing stresses, there
may be small areas of
polarization in an aircraft canopy
or windscreen and, if the angles
of polarization in the glasses and
the windscreen differ, a blind
spot can be produced.
Polarization may also interfere
with depth and distance perception,
particularly during a bank.
Just what you need turning on
final!"
So... be advised.