Come-from-Beyond, how difficult would it be to add a feature to the asset exchange allowing accounts to trust other accounts for a certain asset up to a specific amount? The system would have to be able to handle shifting debt balances.
Not very hard.
I don't know ... is there any reason why the client should not be able to do this itself?
Better not overload the backend with functionality that is not essential to the core
btw, CfB: there seems to be something wrong with the 'sendMoney' function on the testnet, I have been trying browser, webwallet, and my client, but it seems to not work ...