Neither is inherently safer than the other, certificates are about trust, SSL/TLS gives you encryption regardless of where the certificate comes from. If you control both ends of a connection or know the person who signed the self-signed cert and trust him more than someone like Verisign, then yes, self-signed is just as good or better.

In the case of an organisation like Google, I don't see why the US government would even need the keys for Googles SSL certificates. Google have all the data they could ever want stored unencrypted anyway (or at least have the ability to decrypt). If they had any legal reason for wanting the content of my gmail account, they could just get the courts to subpoena Google for the data.

Depends who your perceived thread is really. If you're trying to avoid a government MITM'ing you, sure, in a sense that's more secure.

The chief issue in all this is the huge number of trusted CA that are the default in most operating systems. My install of OSX for example has 181 default certificate authorities, and any one of them could be compromised. I'd be willing to bet that a sizeable portion are under nefarious control.

Just to make a point I picked a random CA and tried to look up some information about it. Couldn't reach their site the first time, as they are lacking an A record on their domain root. I've no idea why they would be trusted, as they look sketchy as all hell — http://www.valicert.com/

Depending on your use case and world-view, they've quite possibly been for a long time, maybe always. You just need to distribute the public part through other channels to the users.

If you train your users to accept self signing you might as well just give up on pki. It appears from the chromium pinning list that they really do let anyone add a pinning rule for themselves if they want to, that would probably be the most practical. I'm not sure of the status of pinning support in other browsers.

No