what sort of powers will corvo posses?

So far we know that he'll be able to teleport, see through walls, possess animals, call for a swarm of rats, "double jump", and there were some others, but I can't recall them right now. One power I really hope will be included is the ability to read an enemy's mind in order to figure out what path they're going to take next, or you could use it in order to learn information which otherwise you wouldn't have been able to learn.

these game is going be great, it will be a lot of fun exploring this world and using awesome powers to kill enemies.

http://dishonored.wikia.com/wiki/Supernatural_Abilities

I said it already but it would be great if we could have the power to "obscure light sources".

I believe he can blow out candles and lamps and stuff using a windblast

Ok, that covers lamps and candles (light coming from fire sources) but what about electric lights?
Instead than relying on weapons it would be cool if Corvo coudl somehow obscure electric lights with magic.

Yes, that would be cool. As far as I know, all you can do about them is destroy them. A cool strategy would be to set up a trap next to a light, destroy the light and draw a guard's attention, hide in a dark corner, watch the guard walk up to inspect the light, and then... you know.

I love the idea of a trap power, much like the "trap runes" in Skyrim (though those often useless).

It's not a power, it is a physical trap. And there are multiple types. However, that is not to say that there won't be a trap power.