If you are thinking of heading down under for the season, the early bird season pass sale is now on. Some are available until end of March, but some are on sale until 13 March only. This link lists all the resorts, their prices and closing dates.
The city of Christchurch as it by a large earthquake on Feb 22 and the downtown area has been badly damaged. The city is the gateway to the South Island ski areas. The airport is on the west side of the city which was not affected as badly by the quake. The airport , rental car companies and many hotels/motels are open for business, so there is no reason to not come for your winter holiday. The city is going your tourist dollars to help recover. As far as I know, none of the ski areas were impacted by the earthquake.