Over on the Official Team Fortress 2 Blog they announced that the update for the Heavy would be coming on Tuesday, August 19th. Appearently, this update is the biggest yet for the game and includes a new game mode, 5 maps for this game mode, 1 additional map for the payload gametype, 3 new heavy weapons, and 35 (heavy) achievements, as well as a “special” Meet The. I really want the soldier and demoman to get this treatment.
[Update]: Valve just posted an additional post detailing the first of The Heavy’s new weapons. The Killing Gloves of Boxing give you 5 seconds of guaranteed crit. But with the trade of off a slower swing rate. They also posted all of the icons and names for the 35 new achievements, but give no explanation of what the achievements actually are.