The trailer itself produces more questions than answers. I would post a few photos and explain a few points but for some reason I can't save the print preview of a video? Looks like you'll have to deal with just text at the moment, and I'll edit the photos in later. If you downloaded the 'Fallout New Vegas Lonesome Road Trailer HD WMV (46 MB)' then flick through to these numbers.
00:30 A new creature for us to kill, however it seems they attack in a pack so beware.
00:31 In my opinion these two red faint dots that move towards the top of the screen seem like two missles yet advanced with a light underneath?
00:39 shows a missle exploding mid-air. This couldn't be a nuclear bomb as the explosion seems too small.
00:58 shows us two red-tanned ghouls with what looks like NCR faction uniform however didn't the NCR simply reuse the old prewar armour? The Divide
could hold several prewar soldiers who can either work for Ulysses who also want America to become the old America or they could simply be
mindless feral freaks who are fun to pop the heads off.
01:02 shows us two people fighting. One being Ulysses and the other could be you, the courior. If you notice, both are wearing the old world flag on the
back of them.
01:05 shows the actual launch of the possible missle we see in the photo of Ulysses. This could either be one of several decisions Ulysses proposes to
us once we finally meet him.
01:07 shows us a legion flag. The Legion obviously have a presence in the Divide, but as of yet we are not sure.
01:11 shows a few nukes exploding. Now I'm not sure but this looks familar to the Mojave near Goodsprings Source, however as I've said I'm not too sure.
01:13 shows us the courior on his possible way home (i.e. Lonesome Road)
All these facts are non-official and are simply my opinion and conclusions/theories behind the trailer.
As I have already said this whole trailer simply gives us more questions rather than answers yet I beleive Ulysses wants to bring back the old America or restore peace to the land. The Legion obviously have a presence in the area yet I have not seen any evidence of the NCR, unless the red-tanned ghouls are members of the NCR? Who knows yet it makes sense for Ulysses to wipe the Divide, possibly the Mojave or even the Headquarters of the NCR and the Legion to cause peace and prevent a war. However this is highly unlikley as that would change the main plot which would be a lot of work for Bethesda.
I know as little as everybody else, so let's wait and show Ulysses who the best Courior is.