For some reason I have not seen this trailer talked about anywhere. I even posted it in the IMDB forums and everyone that has replied said it didn't show at their theatre. The trailer contains: a longer cut of BB in the garage (shorter than showest though), sideswipe doing his thing, a new shot of Arcee, both of the twins talking (something about not being able to read), extended shot in the school library, and more that I can't remember. Just a heads up for you to be looking around for it!Now keep in mind that theatres don't have to bother using any trailers they get so just because an alternate cut exists doesn't mean it will being showing with Terminator 4. Hopefully any alternate cuts that get produced will show up online so Transfans worldwide can enjoy them.
Update: NightShade87 also verifies an alternate cut in the comments, only he saw it with Night at the Museum 2.
At my local theater, I had the opportunity to prescreeen a copy of Night at the Museum 2 and the new cut trailer was on there. Some of the footage was old, but more than half was new. Here's what I remember seeing that was of note:Speaking of Terminator, here is a mix-up of T4 and TF2 trailers called "Transforminator" that Yoboy found for your entertainment.
-Bumblebee crying (Showest footage)
-Twins actually speaking (Sam shows them a tattoo on his arm and they say they can't read. If you listen VERY closely, one of them sounds like Spongebob. XD )
-Galloway and Epps having a conversation that goes like this
"It looks like a normal truck"
*Optimus transforms* (this is a better, fuller version than the T.V. spot)
Epps: "Freaky, right?"
-Better images of Arcee, but I didn't see her fully combined.
Don't remember if there was anything else noteworthy, but I'll make a second look just in case. Please remember that trailers are only selective to certain theaters and it may or may not be on the Night At the Musuem 2 that you watch.