There is a difference between the speed of light being variable
and being uncertain. I have yet to speak to someone about this
issue but my gut reaction is this. The speed of light can be a
constant and still suffer from Heisenburg's uncertainty
principle. 
Also, keep in mind that it is certain pairs of physical
quantities that are uncertain together. I can measure a speed
(momentum) of a particle with infinite precision. I then have no
idea where it is though.
Jason
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Dept. of Physics and Astronomy                  University of Calgary         
jmcvean@acs.ucalgary.ca               http://www.ucalgary.ca/~jmcvean
"I am as close to you as the veins in your neck when I say to you, in 
my whispering lisp, I, too, began as a boy."   Mark Richard - Fishboy
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