Linodes, wherever they happen to be hosted, are under control of a US company and subject to US law. That says all you need to know really. I doubt Linode can say more without risking a holiday in gitmo or facing the wrong end of a drone strike

Don't ya love freedom.
Not that hosting with a non-US company is guaranteed to be different since many countries have similar laws and intelligence sharing relationships. If you value privacy keep off the Internet and if you are likely to be a persecuted minority at some point in the future and must communicate online then you probably need end to end encryption.
I imagine lots of companies already avoid US based cloud and VPS services to comply with local privacy laws and to avoid commercially sensitive information being given to US competitors so I imagine the impact of Prism on Linode business will be minimal.
I wouldn't assume my Linode mail server is any more protected than gmail. Incoming smtp is all plain text and likely captured on the backbone. I talk to it over TLS or ssh but with the keys in my VPS and its backup it probably wouldn't be hard to MITM.