In particular I'm interested in January 3rd to 8th, 2013. But more in general, which events, festivities etc.. are there in Marrakesh?
According to this website, there is nothing special on these dates. The closest to your travel dates are the January 1st (New Year's day) and the January 11th (Independence Manifesto Day 1944). In my experience, I was a January 1st in Marrakesh and I didn't perceived any special celebration.