OmegaX: IIRC it has already happened. Some german guy that had committed several frauds before got some indie developers to agree to sell their games in a PWYW bundle. I think the games included Aztaka and Bob came in pieces. I could be wrong but I think Tantrix denounced that guy here and he was threatened with legal action but luckily nothing came of it and the indie devs decided to leave the bundle.
So does anybody know who is behind IndieGala? Wolfire and Desura are behind HIB and Indie Royale respectively so they are trustworthy but I don't see anything about the IndieGala guys other than that they are from Italy.
gyokzoli: Do you think Gala could get legal Steam keys out of gloom?
Since they are separate keys for each game then they must be gotten from the devs directly and considered "retail" keys. I think each developer that decides to have keys redeemable on Steam has the control over the generation of the keys themselves. For example, AI War and Mount&Blade where the retail keys can unlock the steam-less demo and also be redeemed on Steam.
The HIB is different because they got Valve to create a single key for the whole bundle. I'm not saying that they are frauds, only that it could happen and we don't know anything about them.