- The tech executives do know about PRISM (in fact if not by name) but are continuing to deny it in the hopes of muddying the waters and limiting the damage to their company's brands internationally (this doesn't seem like it would be very smart given that more revelations seem likely, but it's at least a logical possibility).
- The tech companies have employees with clearances who have implemented PRISM at the behest of the government, and non-cleared executives, including CEOs, genuinely don't know what's occurring. If so, they are going to be outraged, and with every right.
- The NSA has gained access to company's internal data via some third party (eg a telco provider to the tech companies, or a hardware or operating system vendor who has provided equipment with a backdoor).
- The NSA has used technical means to break into the tech companies and install monitoring systems without their knowledge or permission (much as China has been trying to do).
- The reporting by the Washington Post and the Guardian mischaracterized PRISM, and for some hard-to-imagine reason, the administration has decided to confirm it rather than correct it or deny it.
I have to say that any of these would be fairly breath-taking. I await further revelations with great interest. I have a feeling there are a lot more shoes still to drop here.
Oh, in an aside, the Guardian is reporting from a supposedly knowledgeable US intelligence source that "We hack everyone everywhere. We like to make a distinction between us and the others. But we are in almost every country in the world" If that's true, not very much of it's been brought to light by the commercial security industry, suggesting that there are some interesting techniques in need of discovery.