I've been thinking about reducing trust in a post-PRISM world a bit today and while switching doesn't help here currently, open source projects are at least theoretically able to prove their trustworthiness by publishing audit tools.

Say for example a distro publishes build scripts which download, verify, patch, compile and package some software using a specific toolchain, anyone could audit this via a simple hash check.

Apple and Microsoft could never prove themselves this way because they need to keep their source code a secret.