So stop your L4D hate DE xD.

Quick rundown:
  • Teleporters and dispensers can upgrade to vet 3, decreasing the recharge, and increasing the ammo/health/metal dispense rate.
  • Spies can recharge cloak by picking up ammo.
  • Updated HUD, showing critical deaths, overheal status, more information when a medic is called for, etc.


They have also said a bit about what they're doing in the future:
  • Scout update is next (thought so), they want to make him better at maps like goldrush and dustbowl.
  • Bringing over some performance tweaks from the L4D engine, like multicore support.


Source

Also read the one below that, it's really funny .