NZPA reports that Green MP Metiria Turei attended national's BlueGreen conferance over the weekend, and that both parties say they could work together in some areas of environmental policy. I'm sure they could - the Greens in particular have shown that they will support any policy that advances their goals, no matter where it comes from. But its drawing a very long bow to go from that recognition of some common ground to support on confidence and supply. Like DPF, I don't see any realistic prospect of the Greens supporting National over Labour if they had a real choice, or of lending positive suport to a National-led government - their members would simply rebel. What's more likely is that in the event National ends up leading a government, the Greens will agree to support various environmental programs which their other coalition partners would baulk at, and possibly gain further concessions by agreeing to abstain on confidence and supply - though even that might be going too far, particularly if the Nats are looking to take us back to the 90's.
What will be more interesting is seeing the potential common ground between National and other parties. In the event they don't elect a Labour-led government (or rather, a Parliament in which a Labour-led government is the easiest choice), the people of New Zealand will be looking to the other minors to moderate National's agenda and make sure there is no repeat of the 90's madness. So it will be interesting to see the positions NZ First and United Future stake out, and whether they will promise to hold National to its claims of newly-found centrism...
