Looks like the top half of a Muton with a rocket pack strapped to their back, and moves a lot like Reapers from SC2. They seem to "swarm" in a pack of 3-4, moving around a lot. Seen from the gameplay footage, Floaters can "levitate" up to fire on Soldiers behind cover. (
http://i45.tinypic.com/333hc7s.png). I guess this is used like an ability and not for constant flying.
Jake does mention teleporting, but it is in the context of flying. I am unsure about any real teleport ability.
"They operate in packs, so they may tie you down here. Then teleport behind the lines and sneak up on you". - JS
However the GTTV article says "Teleport to anywhere on the map."
The more I think about them, the more I like them. Prepare to get
FLANKED X-COM!