I used the deposit using BTC function of the ethereum wallet.
It gave me a deposit address and told me that it will be converted into Ether and sent to my Ethereum wallet address.
I'm still awaiting its arrival after 24+ hours
Did you check the BTC deposit adress you were given via BTC-blockexplorer if your payment from multibit wallet went trough?
Bitcoin has a lot of unconfirmed transactions these days, so small amounts can take some time to reach its destination.
djoser.