The trust model has to include the device/OS/browser/etc that you're accessing the device on as well as all code and keys (including WOT servers, GPG keys, and the webmail code itself, or, if locally installed, all binary packages, updates, etc).
Which I think is the point is really that in the face of a government who can compel, e.g.,
* an OS vendor to install a backdoor in their software, * a microprocessor vendor to critically weaken the Random Number Generator, * the author and BDFL of a key operating system kernel to use said RNG, * a distribution to include compromised or even unsigned packages, * a mobile carrier who will allow random hardware on their network that can sniff, MITM, and inject evil data, * a mobile phone manufacturer who will install CarrierIQ, * (heavens!) a user/customer who visits an app store and installs an application with either a trojan attached or one that is directly a trojan,..
In other words, no amount of end-to-end crypto will save us if we're attacked at each end and in the middle by people who will stop at literally NOTHING (jail) just to get at the data. This is why Schneier wrote "The Government has betrayed the Internet."
http://www.theguardian.com/commentisfree/2013/sep/05/governm...
Encryption is no panacea when you're dealing with someone who controls both ends and the middle. :( To put this on Lavabit is poor form, IMO. This is one end who stood up and fought and paid a huge price.