Is two-phase encryption planned for the standard client? Currently, the standard client supports encryption, but only for actions that change its state (send money, generate address).

I would like the client to require two passwords - one to view any information, and another for mutating it (send money, generate address).

Is this feature planned?
No, it is not planned.

I'd suggest writing some JSON-RPC proxy code that takes RPC commands, checks to see if they're safe (or checks to see what password was given), and if they are authorized forwards them to bitcoind and passes through the result.  There is a lot of good Python code for json rpc clients and servers, although JSON-RPC is a simple enough protocol it shouldn't be hard to create a proxy in any language.