http://www.wired.com/news/print/0,1294,54394,00.html
Interesting read...
"The suggestion that the speed of light can change
is based on data collected by UNSW astronomer John
Webb, who posed a conundrum when he found that light
from a distant quasar, a star-like object, had
absorbed the wrong type of photons from interstellar
clouds on its 12 billion year journey to earth.
"The discrepancy could only be explained if either the
electron charge, or the speed of light, had changed.
"But two of the cherished laws of the universe are
the law that electron charge shall not change and
that the speed of light shall not change, so whichever
way you look at it we're in trouble," Davies said.