Subject: Slowing of speed of light?

I was doing some reading on the slowing down of light performed at Rowland 
Institute for Science. I just wanted a clarification if the photon actually has 
a slower speed or it is the absorption/excitation of the particle the 
photon "hits" which is slowed.  I've read previous questions, however, I'm 
looking for a "one or the other" answer if it exists. Also, I was wondering if 
there could be a substance which sufficiently cooled (theoretically)could slow 
the speed of light to 0 m/s.  If this is possible would it hold similar 
properties to a black hole?  

Re: Slowing of speed of light?