Since I am not anywhere near an expert at any of this, I could be wrong. If I am wrong, I would love to be corrected.
I would think that the absorption and re-emission of light would be more of a starting/stopping thing than an actual slowing down. When the light gets absorbed it gets absorbed at 300,000,000 meters per second. I would imagine that when it gets re-emitted it gets re-emitted at 300,000,000 meters per second as well. It doesn't get slowed down so much as it gets stopped altogether and started again, at the same speed at which it was absorbed. The light itself doesn't get slowed down, but the process of absorbing and re-emitting it just takes more time, causing an apparent "slowing" of the speed of light.
o.O?
I think this is basically what Cap'n Refsmmat said, only more wordy.