Just wanted to share this. A representative of Rockstar that oversaw the previews told GTAV.net earlier today:
It was a fine line, but we managed to carve out a tiny slice, talk about the fundamental changes to mechanics, and keep pretty much the entire game a secret. As it should be. Itís not about lists of features, itís about the being able to hear about the worldís mechanics, look at a few screens or some video of gameplay (and as always, itís almost all gameplay) and imagine the possibilities.