Speaking of which, you should play it
The Lord of the Rings-inspired Helm's Deep Reborn map for Left 4 Dead 2 really was one of the highlights of my journey through the Steam Workshop. It's nice, then, to see a nod from the team at Valve -- the Survival mode-only map has been added to Valve's official servers. Seems like a fantastic way to spend a Friday night.
Additionally, there's been an update which fixes consistency issues with user-created Workshop content and dedicated servers. Be sure to subscribe (i.e., download) Helm's Deep Reborn if you're ever in the zombie-killing mood.