Blizzcon 08 is over and it seems like there really wasn't anything explosive that was revealed as far as World of Warcraft is concerned. Sure a few things were given more clarity and a few issues made known to the devs so they could work on it but there was nothing that made you go "WOW!" (pun intended)
But if there was one thing probably qualifies as a new and cool announcement, it's probably the one about ground mounts being usable in water. This means that when you hit the drink with your ground mount, you'll actually stay mounted. Don't you hate it when you're in places like Un'goro Crater or Nagrand that have narrow bodies of water that separate pieces of land just a few steps apart. Getting to the other side of these pieces of land are annoying because the water is deep enough to dismount you so you'll have to mount up again on the other side. This change that will be patched in after the release of Wrath of the Lich King solves this annoyance.
How, you may ask, will your kodo or nightsaber survive under water without breathing? Well just ask hunters how their pets do it. Though this really brings back the funny thought of having to buy a new mount just because your old one died...