Last time I was in Vail's park was the 24th. They had about 15 features with two very small jumps (6 and 9ft. roughly). That was the Bwana park located on the west side of Vail. A friend of mine on park crew said that they are opening two "medium" jumps in there, they could be open already, I'm not sure. The chair over there is pretty good for lapping.
Golden Peak, which is Vail's best park, is very far from being open I'm pretty sure. They have not even started to make either one of their jump lines or set up any rails.
If you are interested in a particular area, looking for some stashes on pow days, or have any other questions, PM me. I ski at Vail quite frequently. My last general word of advice is that if you are heading to the back (the bowls or blue sky) try to get your shredding done early, as lift lines get ridiculously long here over holiday break.