FTFA:
http://www.fsf.org/news/blogs/licensing/more-about-the-app-store-gpl-enforcement

Basically:

Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein.

In short, I think there are problems beyond DRM with GPL software being distributed through the app store.

Resuscitated.

This is in the FAQ. From TFA:

Q: But what if an attacker takes over all paths to the destination?

A: There are two answers to that. Please see our academic paper for a detailed security analysis.

1) Perspectives actually keeps a record of the keys used by a service over time. Thus, even if a powerful adversary is able to take over the whole Internet (scenario L_server in the paper), clients can still detect the key as suspicious because the key has recently changed. If the attacker is able to compromise all paths for a long time, then you are in trouble, but then again such a powerful adversary could also fool the so-called "verification procedures" of many certificate authorities, which often consist of a one-time email verification.

2) Even though a powerful adversary can defeat the system, it makes man-in-the-middle attacks much harder. Today an attacker must only be on the path between you and the destination, which isn't very hard. Think about an open wireless network, or the recent DNS attacks which compromise a targeted DNS resolver. Being on all links is much harder, and in the end security is nothing but making an attack harder.