Missing argument for option: u
Remember to set rpcuser and rpcpassword in your ~/.bitcoin/bitcoin.conf
before starting bitcoind or bitcoin --daemon
even though I have the password and username set in both the bitcoin.conf and the plist file for DiabloMiner.
I assume you are trying to setup a local server? The error message says that the username is entirely missing. Try reconfiguring by pressing Y + Enter during the first seconds of the application startup. When connecting to a local rpcserver, the username and password you set in the client must obviously match.
So I would add a line that says
rpcserver=localhost
to the plist? What else would need to be in the plist for DiabloMiner? I tried configuring from the command line and the problem just repeats.