http://www.youtube.com/watch?v=9GwZH1vi_mA

Chet Faliszek commented in a thread on the steam user forums with a new line for Bill in The Sacrifice.
In the Left 4 Dead 2 version, not only are the Special Infected included, but the Uncommon Infected are as well. In some of the below images, CEDA Worker Infected and Worker Infected are shown. It is unknown if Valve will release new Uncommon Infected at this point or if they appear in Left 4 Dead also, with or without having their special abilities.
A 190 Page comic book will go into detail what happens before the first game.[1]
The Hunting Rifle in Left 4 Dead (commonly referred to as the Sniper Rifle prior to Left 4 Dead 2, which the interview may have made a mistake on) will be rebalanced to match its counterpart in Left 4 Dead 2[1].
One of the pictures released shows a picture of a bloodied Bill holding a Molotov with a Tank ready to attack him. This might hint that Bill was killed by a Tank.
One of the pictures released show Francis with one foot on a low wall. Next to him is a jukebox, meaning like in the previous DLC, there may be a jukebox here too, possibly with another new soundtrack in addition.
One of the Pictures released shows the Player wielding the M60, meaning this may be the second Campaign in which it becomes available.
In the interview with Chet Faliszek, Louis is seen in comic format talking on a phone and to the left is a Heavy figurine from Team Fortress 2.
The finale is said to be a "new style" of finales, where the Survivors will have to complete three separate objectives.
Supposely, the finale of this campaign is going to be on the same location as The Port in The Passing.
It is unknown whether the Tank and the rest of the original Left 4 Dead Special Infected will appear as they do in Left 4 Dead or as they do in Left 4 Dead 2. However, the Tank in the artwork of Bill in one of the pictures below has his appearance from Left 4 Dead 2, and since the end of The Sacrifice supposedly takes place right before the beginning of The Passing, the Special Infected may have their Left 4 Dead 2 skins.
Alternatively, it is possible that the Special and Common Infected will keep their appearances from either Left 4 Dead or Left 4 Dead 2 depending on which game you play the DLC on.