The developer posted this on his blog:
Previewing the 1.0 that is coming out on Steam this month! Everyone who has previously bought the game will get a Steam key, don’t worry
He also posted this video of 1.0:
Some gameplay 5 min in, looks pretty cool.
I'm guessing that everyone that owns Humble Indie Bundle 2 or 3 and activated the Steam codes for them will get this game added to Steam automatically.
This game page already has a releasedate, I'm guessing that is for the alpha. That should be changed when we get a real date right?