I am pretty sure it cannot, that would defeat the whole purpose of SSL. SSL (iirc) is based on symmetric encryption which have one private and one public key for each session/connection and only one of them can be used to encrypt and decrypt the other. Hence why it is not possible to sniff SSL because you dont know the required key. You could brute force it but that would take millenniums.
That would be indeed true about SSL. I will definetly take a look into the HTTPS: portion however. I was just going off of what I have read around the interwebs about Ettercap. (Haven't had a chance to put it into practice.) However, if a program like ssl strip could do it I can't see why that wouldn't be a "feature" of ettercap if you start messing with the conf file. I dont think if you go to your local wifi hotspot start sniffing the network you will get plain text but it may or may not give you the encrypted data.