White-tailed spiders are common in New Zealand houses and sheds, where their most common prey is the grey house spider (Badumna longinqua). They have an undeserved reputation for bites that can supposedly cause large, necrotic ulcers, but sound evidence for this is lacking. The bite has been documented as being painful, though, so I treat them with respect when shifting them outside. If you want to know more about these spiders, including a clear discussion of what's known about their bite, I recommend the Landcare Research page on white-tailed spiders.
On the basis of the known distribution of the two species in New Zealand (Australia has 61), I assume this is Lampona murina. It's certainly a male: the mark that looks like a slight depression on the abdomen where it joins the cephalothorax (the front part of the body) is not present in females. I managed two photographs of this one after moving it from the kitchen to the verandah — then he was gone.
[26 November 2013, Olympus OM-D EM-1, 60 mm f2.8 Macro , ISO 200, 1/60 at f8]
All content © 2013 Pete McGregor