Gizmodo had spotted different color models for the Zune HD in the Zune software source files some time back which included pink, magenta, purple and atomic. The magenta and purple colors have now popped up on the Zune Store and will be available on the 1st of December.
Currently the 16GB version is available in black only, while the 32GB in silver. No idea yet which capacities will these new color models be available in.
On a related note, there’s currently a holiday sale up at the Zune Store. If you buy a Zune now, you’ll get a month of free music and free inscription and all 80GB/120GB devices will receive a free A/V pack. Good time to buy a Zune!