The NZ Herald has a good article on possible coalitions and what policy similarities there are, and what differences there are:
The option with the largest differences is (despite the spin) Labour and Greens, being:
* Any commercial release of GM organisms into the environment
* Sending defence personnel to hotspots such as Afghanistan
* Barriers to foreign investment and land sales to foreigners
* Role of intelligence agencies and in the international intelligence-gathering network
* Cutting beneficiaries out of Working for Families payments
* Reforming cannabis law
* Joint regulatory agencies with Australia, such as food standards and therapeutic products
If there is a Labour/Green Government, then I expect it would end up like Labour/Alliance did – the minor party torn apart. And the reason for this is not that the MPs will not be pragmatic, but their supporters will not be and in fact can not be.
Green supporters, like Alliance ones, are passionate about foreign and defence issues especially. And they will find it intolerable to be part of a Government that has the SAS in Afghanistan working with the United States. They won’t care about the consequences of not working with the United States because they honestly think the United States is the most evil country in the world.
Remember this is the Green Party which a few days after September 11 led a march against the United States taking any retaliatory action at all. In their world the US would still be sending notes to the head of the Taliban asking them to co-operate or we will write a harshly worded press release.
And also no matter how much one has an agree to disagree policy, signing a free trade agreement with China would put huge pressure on any Government with the Greens in there.