Last night, they along with WikiLeaks founder Julian Assange -- who also appeared by video link -- and Canadian human rights lawyer Robert Amsterdam were greeted like rock stars by the audience of 1700.
After the cheering and applause that greeted Snowden's appearance died down, he told the audience: "There are actually NSA facilities in New Zealand. One of them is in Auckland, another is in the north of the country."
The event took place shortly after Snowden claimed in an online article to have evidence of mass surveillance of New Zealanders' electronic communications by the NSA and the GCSB, a claim dismissed by Prime Minister John Key.
Greenwald, who has clashed with Mr Key since arriving here several days ago, introduced Snowden as "a hero" for his work exposing NSA spying.
"Even his harshest critics have not been able to say anything he has said about surveillance is unreliable or untrue."
Greenwald fired another salvo at Mr Key last night, saying the Prime Minister had misled the public over the reasons for passing GCSB legislation last year.
The law was required to legitimise the mass surveillance programme, he claimed.
He said a NSA slide published on his Intercept website yesterday showed the first phase of the so-called "Speargun" programme -- tapping the Southern Cross cable -- was completed in mid-2013.
He claimed another slide showed the GCSB was awaiting the passage of the legislation before proceeding with the second stage, inserting a "metadata probe" that would allow the collection of data.
"These documents show that he [Mr Key] was not telling the truth."
In his article yesterday, Snowden said: "If you live in New Zealand, you are being watched."
In his work as an NSA analyst, he claimed, he routinely came across the communications of New Zealanders and that data was obtained by tapping the Southern Cross data cable.
The information was available to NSA analysts through a surveillance tool called XKeyscore.
Last night, he said the GCSB not only used the tool but had helped to expand and develop it.
"XKeyscore does involve both the metadative [metadata] and content ... for individuals in New Zealand. That is without question. Citizens of New Zealand have their private communications in this database."
Key: No 'cable access surveillance programme'
Key: 'No recollection of the conversation'
Mr Key responded to Snowden and Greenwald's claims ahead of last night's meeting, saying they were based on incomplete information.
"There is not, and never has been, a cable access surveillance programme operating in New Zealand.
Mr Key released a series of documents "to set the record straight" which he said showed that what Snowden and Greenwald were referring to was a cybersecurity programme which had been scaled back over concerns it would be perceived as mass surveillance.
Earlier, the Prime Minister acknowledged that project did involve putting "a probe" across the Southern Cross cable but he said the probe was never used.
Cunliffe: More detail needed
Labour leader David Cunliffe told RNZ that New Zealanders deserved to know the truth about the workings of the spy agency.
"Not the micro level details, that's not appropriate...and I'm not questioning that there are valid roles for the protection of New Zealanders by the security agencies.
"What I am saying is that some new questions have been asked here that go to the heart to how this is done and at a high level New Zealanders deserve truthful answers from the minister responsible, who is the Prime Minister."
Mr Cunliffe said there was less than a week until the general election and Mr Key needed to make a clear statement about whether New Zealanders were under blanket surveillance by the Five Eyes partners.
"Is that information accessed by the New Zealand authorities - if it is, under what policies and protocols."
He said he was "no big fan" of Dotcom
."But these issues go beyond any individual, these issues go to the heart of our system of government in one of the most sensitive areas."
The assurances Mr Key had given the country about mass surveillance did not match with information given at Dotcom's event last night, Mr Cunliffe said.
"The prime minister said no blanket surveillance, that's not what it looks like."
Mr Assange, speaking from the Ecuadorian Embassy in London, told last night's meeting the Five Eyes surveillance network was a "radical extremist project" and part of a "bizarre Orwellian future".
Mr Amsterdam, who is helping Dotcom to fight copyright charges, warned the audience: "Our governments are trying to alienate us from each other, and they are using terror to invade our homes, to invade our internet accounts, and to engage in mass surveillance that is violative of our most basic constitutional rights."
US analyst: XKeyscore not necessarily illegal surveillance
Bill Arkin, a US national security analyst, said he believed XKeyscore was being used in New Zealand, but that didn't mean it was illegal surveillance.
"Using XKeyscore and being a member of this [Five Eyes] partnership and being engaged in the collection of what is called raw, unselected, bulk traffic does not necessarily mean to me that people in New Zealand are illegally being surveilled," he told Newstalk ZB radio this morning.
Snowden had "very ably demonstrated" that mass collection of information was capable, but Mr Arkin said he was "still agnostic on the question as to whether or not innocent people are being surveilled".
"What I see is just a collection system that is out of control and I'm not quite sure at this point that there's any evidence that indicates that a normal New Zealander who is not engaged in terrorism, crime, or some other illegality, that their communications would ever be looked at," he said.
"Do I believe there's mass surveillance? Yes, like the sun shines there's mass surveillance. Is it actually violating the civil rights of anyone in New Zealand? Well that is what we need to determine."
He added that it was "far from clear" if the programme posed any threat to the civil liberties of New Zealanders.
