Apparently Guillermo del Toro is not creating a trailer for Deadman, and the rumours of such have angered the Producer Don Murphy in a typical Internet flaming type of way.

Del Toro is actually creating a trailer for Mountains of Madness, although how anyone was supposed to know that without an official statement is beyond me, so when he stated that he was doing a trailer for an upcoming film to prove it's worth to the studio, /Film thought this meant Deadman, and why not? No one said otherwise.

Now though the word is that he meant Mountains of Madness, another film he wants to do. Film Ick had Don Murphy commenting on their post about the subject and while he was polite to Brendon in his comments, as soon as he got back to his own site he ranted like a typical five year old Internet flamer. In a post entitled Internet Retards, his words, not mine, he talks about the /Film article:

except they didn't interview Guillermo or at least didn't take good notes....
because he is NOT doing a trailer for Deadman, there is no script
he is doing one for AT THE MOUNTAINS OF MADNESS.
so now this idiot issues this bs story and it is picked up by other idiots and I cannot even email the loser because you have to be a member and I signed up and nothing happened.

Okay, so it's not true, but to insult all these people in this socially and gramatically inadequate manner is the exact behaviour of those so called "Internet Retards" that he was talking about, although I don't like using such a negative and insulting term. It's especially pathetic when you're nice in the comments of a post and then go off and shout out to the world this kind of inflammatory commentary.

Anyway, idiots aside, over at Dark Horizons they manage to make sense of how the confusion happened and discuss the possibilities (rather than behaving like a child), and although there's still no clear answer it looks like his comment below relates to Mountains of Madness:

"What happened is, I've gotten an incredibly beautiful offer from Warner Bros to finance a trailer. So they said we'll finance a trailer so that you can show us what you see the movie being like. And I'm going to storyboard and script a little three minute trailer "