Wikipedia: The Humble Bundles (previously known as Humble Indie Bundles)
This is notable change. Now they are officially "just another bundle".
This one is a Humble Indie Bundle - the change of the overall naming is because they now have other bundles too (like the THQ one). The other bundles are still "pay what you want" and a lot of the money goes to charity. I don't think it hurts the Indie bundles by having more of a good thing.
Is the Grimrock Linux port available on Steam now?
I purchased the Windows version some time ago.
BTW, awesome game!
None of the HIB games are in the Steam beta yet. I guessing Valve wants to keep attention focused on a small set of games so it's easier to figure out general problems before having to deal with a lot of game specific issues.