Looks like the legendary weapons are finally starting to appear in the world of Tyria.
Over at GW2Guru, there have been two users posting pictures of their rather epic creations. XalkyriezzZ has posted picture of his Bifrost, which he claims to have had the materials for since September 23rd, but was stalled due to a bug at the Temple of Balthazar. You can find his thread here.
Now, both threads claim to be the worlds first legendary weapon. No official word yet on which one is first, so we shall have to wait and see. No doubt many more legendary weapons will start appearing as October trundles on.