The new Washington Post iPad app has dropped with a high production quality video featuring legendary American journo Bob Woodward, among other luminaries of US media. See the trailer:
Trailers for apps are becoming a trend. For example see the amazing New Yorker iPad app video featuring Jason Schwartzman and directed by Roman Coppola (as you can tell by the style):
If I had to speculate, I would think this trend was probably spurred by the amazing Adam Lisagor (aka lonelysandwich) whose trailers for products such as Square (see all of the spots), Flipboard and Jambox have set the tech and design community alight.