Fwiw, the Ethereum Foundation has someone working full-time on formal verification systems, and the online solidity compiler has a partial implementation of formal verification for smart contract sourcecode.
Aside from that, the DAO disaster has made people realize they need to build backup plans into their contracts. Maybe you can't change sourcecode at will, but you can add emergency shutdown mechanisms, predefined paths for upgrading code via systems of modular contracts, etc. There's a tradeoff vs. trusting the admin, but for now it seems like a good one in many cases.
Aside from that, the DAO disaster has made people realize they need to build backup plans into their contracts. Maybe you can't change sourcecode at will, but you can add emergency shutdown mechanisms, predefined paths for upgrading code via systems of modular contracts, etc. There's a tradeoff vs. trusting the admin, but for now it seems like a good one in many cases.