Also included in the post is the fact that the speed boost itself will be increased very soon. Horses will be slightly faster, and Mammoths and Rhinos will get a smaller boost. As well as this, to address a complaint that those with Mammoth/Rhino pre-order privileges have, the riding skills (charging, attacks, etc.) associated with these mounts will be given automatically with the "/claim" command after a future patch, and those who already have the skills through buying Basic Riding will need to perform the command to receive them again.
EDIT: Going by this forum thread, the mount speed increase is already in effect as of today's patch. Some in-game testing of our own shows that at the very least, the bug requiring weapon sheathing/unsheathing is fixed. More on these other undocumented patch changes shortly.