Client Encryption of local wallet?

[bitjet]

Would it be possible to create a secure client, to have the bitcoin client keep the wallet encrypted even while its active? A password protected client i guess. The client could be configured to show status of wallet but require a pass-phrase when sending a payment or something. I dont know just an idea, with the value stored in wallets going up this only seems like a logical solution. Forgive me if this has been discussed.

[Pieter Wuille]

This is a planned feature for 0.4.0.