I didn't see it posted here in the forums, so I thought it would be a good idea to throw it up here for those that don't know.
Anyway, ValVe's decided to get the guy that made Two Evil Eyes to make a new community map called Cold Stream, set to be released some time after Portal 2. It'll also include the other three maps from the original L4D, so they say.
Since The Passing and The Sacrifice were both story-heavy and not very Gameplay-heavy (come to think of it, there wasn't a lot that those two maps added in terms of variation. You could argue that The Passing was better than the sacrifice, since it added more elements to the game than The Sacrifice did, which only added two new maps and let those playing L4D2 play as the original cast) Cold Stream will be focusing primarily on gameplay, rather than story.
Here's the blog post:
http://www.l4d.com/blog/post.php?id=5019Here's the forums where ideas for the new map are being posted:
http://forums.steampowered.com/forums/forumdisplay.php?f=1088Personally, I think it'll be a nice addition to L4D and L4D2, since It'll end up reviving both games immensely. Seriously, the Scavenge maps are pretty much don't exist as far as the majority of people in L4D are aware.