A quick note to anyone buying the Humble Indie Bundle 4: if you want Steam keys you'll have to pay at least $1 USD for the bundle. According to the official blog for the promotion, some "un-humble" buyers are paying one cent for the bundle and using/reselling the Steam Keys to game the Steam Holiday promotion currently underway. More from the blog:
"Hey guys, we’ve noticed that a number of un-humble users are buying lots of Humble Indie Bundle 4’s for one penny, and then using their Steam codes to 'legitimize' automated Steam accounts in order to increase their odds of winning prizes in Valve’s current raffle promotion. This is unfair to legitimate entrants and is definitely not what we wanted to encourage with Humble Indie Bundle 4. It’s a lose-lose situation for the indie developers, charities, Valve, and Humble Bundle.
Therefore, starting immediately, new orders under a humble threshold of $1 will not contain Steam keys.
If you can’t afford a dollar but still need a Steam key and promise not to resell it or otherwise abuse it, please contact our support team with your humble appeal and we’ll purchase a new bundle for you on a case by case basis."
While some might complain that this goes against the whole "pay-what-you-want" nature of the bundle promotion, others argue that spending a penny and then trying to manipulate a rewards system is much more nefarious.
For those interested in buying the 12-game bundle for more than $1, check out humblebundle.com