Blizzard has released a lot of new information about the burning crusade... small things like the actual flying mounts we will get to fly as well as more important things like how the pvp system will be revamped and 40 man raid instances will bite the dust. Jewelcrafting looks like it will be interesting adding a whole lot of customization to your character and the outdoor pvp that they are starting to implement in 1.12 will continue throughout all of the new zones.

Just because there is no 40 man content dont think that the new instances will be push overs. I've heard that one of the 25 man instances will only be reachable via flying mount. (that doesnt speak for its difficulty but it does sound really sweet).