A Team Fortress 2 Pyro Update has the list of Pyro achievements and unlockables for tomorrow's Team Fortress 2 update. The update will also include a pair of community created maps, and these are detailed as well. Here's a bit:

In addition to the three unlockable Pyro weapons, we've made a significant addition to the base Pyro flamethrower. By hitting the alt-fire key, the Pyro is able to produce a blast of compressed air that knocks enemies away, and redirects enemy projectiles. It’s a highly versatile tool, allowing Pyros to get away from nearby enemies after igniting them, to kill enemy soldiers with their own rockets, or to separate enemy Medics from their healing targets. In particular, it allows a skilled Pyro to contain an enemy invulnerability push, and even to separate the Medic completely if the surrounding terrain supports it.