Hi Alex,
Yeah, this is awesome news. I encourage anyone who would be happy to help organise anything (from JSConf's or NodeConf's to JSCamp and NodeBots days) go over there and join and say hello. Or just lurk. Hopefully when things start happening, we'll be looking for volunteers to help with anything and everything.
Feel free to post this link to the Node Night Wellington group, and I'm sure others in the Auckland and Christchurch groups can do the same. :)
Cheers,
Andy