In an interview with Jordan Oloman for NME, Valve's Kerry Davis clarifies that most of the work in the update is indeed straight from the community.
Not content to stop there, the update features 'hundreds of bug and exploit fixes' along with other new additions, like previously unused voice lines for the survivor characters. The team responsible for the update is also adding additional maps (four for scavenge mode and a whopping 26 for survival) and some new weapons (a shovel, pitchfork, and some guns from Counter-Strike: Source).
