This is the "Direct Hit". It's a new rocket launcher for the Soldier, which is aimed at those who, well, like to aim. Its splash damage is greatly reduced, but in exchange, it's a lot faster and more powerful than a standard rocket. It also does extra damage on airborne targets, so if you've been trained to jump to avoid a rocket's splash damage, might want to keep your feet on the ground for the next few weeks.
In addition to the upgrade, there's yet another TF2 comic, along with the news that anyone sitting on the sidelines who is at all curious about what all this means, this weekend will see TF2 go free-to-play. Hell, it's not even a weekend; it starts on Thursday, meaning you get four days with the game for free.