geth show "primary" account

[ethers]

2 quick suggestions. When running geth account list modify the output like this:
Welcome to the FRONTIER
Address: {29d33c02a200937995e632c4597b4dca8e503978}
Primary Address: {57b723e224954a3026c1fb44c5f07b4b5fc096a8}

Or add an option to geth account.
geth account has:

COMMANDS:
list print account addresses
new create a new account
import import a private key into a new account
help Shows a list of commands or help for one command