I think the "real" trailer stands its best chance yet of appearing before Beowulf which opens on November 16th. However, some critics and a lucky few will see early or advanced screenings. I didn't spend too much time on this, but I see that one such screening will take place on November 9th. That's in less than two weeks.
OT: I'm trying out "threaded" comments, so if you know of an earlier advanced screening of Beowulf, do me a favor and drop your info in a comment.
Update: So says CommingSoon:
All has been relatively quiet on the 1-18-08 front for the last few months since the San Diego Comic-Con, but a source for ComingSoon.net has revealed to us that the J.J. Abrams-produced monster movie will get a new trailer AND its title will finally be revealed on November 16 in front of Robert Zemeckis' animated Beowulf.And /film:
I’ve been hearing in the past couple weeks from a number of sources that a new 1-18-08/Cloverfield movie trailer will premiere in front of Beowulf on November 16th.Tags: 1-18-08, Cloverfield, Slusho