Apple, Facebook and Google all said that they did not allow the government direct access to their systems and had never heard of the Prism programme. Facebook's founder, Mark Zuckerberg, called press reports about Prism "outrageous". But the Guardian presented a slide from a top-secret NSA presentation and reports in the Washington Post and the New York Times, it was becoming clear that some major technology companies have bent over backwards to make it easier for intelligence agencies to access the information they want.
Only Twitter and Amazon appear to have refused to co-operate. What appears to be happening is spin. The tech companies' denials have concentrated on suggestions that they had given the NSA "direct access" to their servers. This comes from a Prism presentation slide that states: "Collection directly from the servers of these US service providers: Microsoft, Yahoo, Google, Facebook, PalTalk, AOL, Skype, YouTube, Apple."
But it appears that the PR people are splitting hairs. The system was that secure online "rooms" were set up where requested information could be sent and accessed by the NSA. Not exactly direct access but pretty much the same thing. The Prism system allows agents at the NSA to send queries "directly to equipment installed at company-controlled locations", rather than directly to company servers. Again this allowed plausible deniability.