Update!
Actual and official Fallout 3 trailer with ingame footage.
EDIT- I've been playing the Too Human demo for a bit now, and have decided it's worth a purchase. I've been hearing tell that there's a way to unlock the four other classes. Thus far, two methods have been introduced: The first is to unplug the ethernet cable from the console and change the system clock to 2009. The second is to "mash A" whilst cycling between the classes... I mashed A to no avail. Can anyone check if the other way works? (I would, but I'm at work :P)
UPDATE: Here's the video showing you how to play as the other classes.