The Warp Ray has been added to the official site:

http://www.starcraft2.com/features/protoss/index.xml?tab=warpray

I'm a little confused as to what the difference is between this and the colosus. The only things I have been able to pick out are that its an air unit (can't be targeted by ground), and it apprears to be specialized for buildings insted of small units. I guess this is enough to make them different, but the origional game did a great job at making every unit almost complete unique within each race.

It looks like the Warp Ray is a kind of artillery unit specialized for taking down anything with a lot of hit points. Like the Colossus, the Warp Ray has a continuous wave beam weapon, but there are substantial differences. Whereas the Colossus' weapon stays on all the time, doing "splash" damage to units in the arc between its targets, the Warp Ray's weapon turns off while acquiring a target and takes time to focus on its target (bringing up to 3 streams of energy to bear on the target). The Colossus seems to be good against massed infantry (zerglings, marines, etc.) due to the sweeping of its weapon. The Warp Ray is effective only when it can concentrate on a target. I would imagine that a number of smaller units like Wraiths could swarm the Warp Rays and take them down easily, especially if the targeted Wraiths kept flying out of range, forcing the Warp Rays to select new targets.

If I am remembering the gameplay demo correctly the warp rays big deal is that the longer it stays on one target the more damage it does, so against a large target such as a terran battleship it is very effective.