Not terribly many as yet. There's quite a lot of resistance to the building of new infrastructure of this sort - rampant nimby-ism mostly backed up by the Resource Management Act. Personally, I want to ask wether the objectors would prefer a nuclear power plant. It's not insurmountable though, ground was broken on a new wind farm at Makara, behind Wellington only a few days ago.
There are a couple of wind farms and quite a few single turbines around. http://www.windenergy.org.nz/ This one was built more as a proof of concept over 10 years ago.