Yes, it's permanent, within NZ. It's travel conditions that expire after two years, so the Residence could lapse if you were outside NZ at that point.
Remember, the application form requires everyone to state that they have the means to support themself (and their family, if applicable) for two years, in the event that they don't find work, or aren't applying with a job or offer. As far as the NZ government is concerned, a Skilled Migrant is coming to contribute to NZ society, not to take from it.
After two years spent in NZ, after having activated the Residence visa, a person could claim unemployment benefit, subject to conditions. I believe there are benefits available before that, for instance, if children are in dire need, but they're for extreme circumstances only, and means tested.
This page and its links may be of use.
http://www.cab.org.nz/vat/money/ben/...formation.aspx