The Sacrifice update is now out. Beware, L4D2 owners, the update is over 3GB! No idea what it is for L4D1.
Its about time Valve combines the games into one. If you have both L4D1 and 2 installed, you have a lot of wasted space and bandwidth. You'll be downloading The Sacrifice twice, plus a duplicate copy of No Mercy (with all the sounds, maps, textures, etc). Just seems stupid how its been done.