No one is denying PRISM exists, it just needs to be abolished, and all things like it should be subject to public scrutiny. Obviously it's not ineffective when it's not a secret, so there is no reason for secrecy.
That's not true, the slides describe a system that receives a raw data flow and decodes it. Google and Facebook have both explicitly denied giving access or even receiving a request for blanket or bulk access. They both say the have only received requests for specific individuals, and every request is individually reviewed by their legal team.
There's nothing to see here, people. The participating companies are not actually participating at all, and a damage control press release is absolute, unquestionable confirmation of this fact. Nothing is more truthful than a press release.
It makes even more sense when you consider the name of the program "prism" is an object that's capable of splitting light into it's colorful components, i.e. decoding the data streams into visible readable more colorful data streams. Each company is a color exposed by prism.
It's not an acronym. It's a play on words.
Tech: All the companies listed have multiple sites/datacenters. While they use SSL/TLS to encrypt client-server connections, they may not be using encryption to protect server-server connections. Most of the database replication systems don't use encryption by default. Companies use circuit switched connections between sites, they don't own the fiber between two datacenters. That fiber is owned by the big telco providers, and passes through equipment owned by the telco providers.
We know big telco providers like AT&T and Verizon are very willing to give the NSA access to everything without putting up a fight. It seems very possible to me that the NSA is surveilling these companies without their knowledge.
For example it was reported that Dropbox was "coming soon" to PRISM. I don't believe for a second that Dropbox is knowingly giving access to the NSA. "Coming soon" may mean that the NSA has tapped Dropbox's communication, and they are working on decoding it, and converting it into a usable format for PRISM.