The Washington Post articles keep referring to companies/providers as "participating", but no where in the slides does it say that internet companies are knowingly participating. It seems very likely that the companies listed are unaware of the surveillance, and the dates listed are when the NSA was able to tap and decode their data streams. I would really like to see evidence that companies are knowingly participating, otherwise this may be defamation by the Post.

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.