Ah, September. That time when the leaves begin to green, the morning air is crisp and Valve's modellers and animators vanish from Team Fortress to work on Left 4 Dead.
Happened last year, it's happening this year, as Team Fortress 2's official blog says in an update. "We've improved our process a little to ensure we can keep some people on TF2, enabling us to continue doing TF2 updates," the post says.
The news they have is of utility most to the modding community, however: the Source SDK has been updated to include the model and animation source for Heavy. "Take a look at it, and be sure to send us your thoughts."
Valve had hoped to supply more but with the lack of manpower, "We decided it'd be best to get one model out, if only so we could get your feedback on it before we went ahead and got the rest done."
Also of note in this blog update, you can pick up the official "ubercharged" avatars (pictured) in a zip file should you wish to comment as an extra-satanic looking Heavy or something.