There are 3 sci-fi 'punk' genres:
1. Cyberpunk (matrix-esque)
2. Steampunk (Victorian era)
3. ? punk (World War 1 & 2)
I'm not sure what the 3rd one is called.
Cyberpunk is a bit old hat now. It was inspired by William Gibson's 1984 book Neuromancer. Steampunk featured in Gibson's book The Difference Engine.
Essentially, the 'punk' part is a kind of irreverence for the technology; an attitude of indifference.
http://en.wikipedia.org/wiki/Steampunk
