A few days ago I killed a dragon that attacked me near Riverwood, I passed through there yesterday and the skeleton seems to have sunk through the world mesh. What remains is the dragon skull looking skywards like some tomb marker, looks brilliant.

Yeah, I'veh had this happen a few places too (I've killed some 20 odd dragons now). I don't know if it's a 360 specific issue or not, but Dragon skeletons migrating from place to place within a town, once killed, does seem to happen quite a bit for me. Intersecting buildings and the landscape. I have a feeling it has something to do with returning to locvations using fast travel. Not pinned it down yet though.

It's on the PC too, it's something I hope they fix in the first patch. Dragon skeletons spawn when you enter their region by falling from the sky and they end up spawning all over the place, it's annoying.

Dead bodies within a cell have this annoying property. I killed a frostbite spider right outside Morthal. Fast traveled elsewhere, fast traveled back to Morthal, and a frostbite spider corpse fell from the sky right in the middle of Morthal, right in front of a guard who was justifiably surprised.

In Riverwood i killed a dragon and the skeleton is hitting this shop sign over and over so it swings around like a merry-go-round. Its like the dragon is still alive just enough to haunt the good people of Riverwood...

The worst I had was after killing the Dragon at Kynegrove. When I re-entered Kynegrove not only did the dragon keep falling from the sky, or popping in and out of buildings, but it had its skin back on too. Landed right in front of me when exiting the mine once. thought it was a new attack at first. It's head was sticking out of the ground once too.