PC-IGN has posted an article after visiting with the Age of Conan folks during today's GDC. Including a look at city building and mounted combat, here's a snip of what the editor had to say:
Moving beyond the dungeons, we were shown a brief demo of mounted combat, which differs depending on what animal you're seated on. Special animations are built in as you climb aboard, such as the epic mammoth mount bending down to accommodate you. There's also an epic rhino mount, which according to Funcom was put in because they liked the movie 300 so much. While riding you can still use your left attack, right attack and such on the quickbar, and the horse mounts can kick backwards and forwards. Momentum plays a role in attacking as well, as the faster you run on your mount, the more damage you'll do. The damage calculation is also based on weapon type and skill as well. Every mount has a different kind of handling, meaning something like the mammoth will require more room for acceleration and a larger turning radius. Funcom states it's similar to how the cars' handling in the Grand Theft Auto franchise differs.
In PvE you can use these mounts to break outdoor camps and access new areas. In PvP there's more to it because movement and speed come into play. Mammoth and rhinos can even be used to attack walls and buildings while assaulting cities.
There's much more to the article for the Conan fan.