He's confirmed the appearance of the Space Jockey, or more accurately whatever was housed in the Jockey armour: 'I was always amazed that no one asked who the hell the Space Jockey was. He wasn't even called the Space Jockey. During the film they started to call it the Space Jockey. I don't know who started that one off. I always thought it was amazing that no one ever asked who he was, and why was he there? What was all that about? I sat thinking about this for a while and thought, well, there's a story! And the other four [films] missed it! So, here it is.'
He also says that original Alien designer H R Giger has been consulting on the film, and in a final flourish revealed whether the xenomorphs with which we're all familiar with will be making an appearance.
'No. Absolutely not. They squeezed it dry. He (the xenomorph) did very well. (He laughs) He survived, he's now in Disneyland in Orlando, and no way am I going back there. How did he end up in Disneyland? I saw him in Disneyland, Jesus Christ!'
So there you have it. Alien DNA. Giger. Space Jockey. But definitely, absolutely no old-school alien. Unless of course Ridley's telling us some fibs. In the trailer preview (yes, trailers now get their own trailers) that does look like acid burning someone's helmet. What was it that bled acid again...?

