That's what I think as well but this is the fifth Humble Bundle and it's not even the official announcement, simply an addition to the original deal. I'm just a bit surprised this is of interest to so many HNers.
The Humble Bundles are the only reliable source of high-quality Linux-compatible games that I'm aware of, so I expect them to continue to get a fair bit of attention.
Though I voted this submission up because of its informational value. I saw it before I got an email about the update.
The fact that these are all compatible with linux and mac substantially increases their interest for a lot of people here, I think. HB's make up a pretty big percentage of my game purchases on my mac.
This may be the fifth one (actually more, if you count the Bundles that were developer-specific) but this time around the games in it are excellent. It's probably the best of their bundles ever. And the new games only add to that.
