gyokzoli: No key, you can redeem the game directly to your Steam account. Just bought something a couple of hours ago in the Humble store.
Pheace: Thanks
Or, if it's really a friend that you're sending an activation to and you're not restocking CheapLatverianGames.com, then you can disconnect your Steam ID from Humble. Then have your friend connect theirs, activate the game, and disconnect again. Should the license provide a little giftbox button, you could click that, too.
In on-topic news, I don't think anybody really captured how much the Humble Store has on sale right now. There are 9 pages of games on sale, and one page at regular price. As for the two bundles that are live right now, can you tell which one is DRM FREE? Funny how they've dropped the icon for that, almost like they want to get away from that old-n-busted brand.