I am running multibit. I have less than half a bitcoin. I realised today that I have totally forgotten my password. My wallet is still open so I can still use it to pay for stuff. Can I create a new wallet in multibit and transfer the bitcoin balance to that without having to retype me password or logging out of my current wallet?
Multibit will prompt you for a password regardless of whether you are sending it to your own wallet or not. This is by design, since if it didn't do this, it would allow anyone who can access your laptop to transfer bitcoins from your encrypted wallet by sending it to the unencrypted wallet first.
Sorry but unless you made an unencrypted backup of the wallet in the past, your coins are lost if you can't recover your password.