Here is the link to the up to date thread: http://forums.steampowered.com/forum....php?p=8794262

This link includes:

Weapon Statistics (as accurate numbers as his testing can get)
Infected Statistics (Hp, hitboxes, damages)
Movement Speed
Versus Scoring - (credit goes to http://left4dead.gameriot.com/blogs/...comment_326190)
Weapon Penetration
Vision (same as the earlier visibility post)

On Friendly Fire

Survivors have no hit locations.
Survivors will report being hit by FF if bullets fly very close without hitting them.
Friendly fire damage is reduced by damage dropoff based on distance.
Survivors are immune to friendly fire on the lower legs.
Survivors will report being hit by FF if bullets fly very close without hitting them.
-Phoebus

There is a front and back hit location on survivors. Normally this doesn't matter, for versus setting. It doesnt seem like he did any testing on normal infected damage. But as you know, this damage is something like 1/2/5/20 (easy-expert), with damage changing depending on whether the zombie hits you from the front or back (I only verified this on expert so I don't know if this applies to versus on normal. However, it does apply on versus expert where damage form normal infected change depending on where they hit you from). This acts as a penalty for letting normal infected hit you from the front (ie swarm).

Same as why a infected is killed by melee to the back and not to the face or balls from the front. Furthermore you can squish zombies as I mentioned a few days ago as a survivor.

Friendly fire - FF damage is determined by distance (weapon damage drop off) and weapon damage. The game compensates for erratic movement from teammates before applying friendly fire damage. This is why you often see you hit someone only for it to not deal damage. You can try this by shooting your buddy in the foot.

Legs are not immune to FF damage. Bullets that are "close" to survivors which do not hit them, do not trigger FF warnings. Bullets that seem like they miss, but hit, is probably due to lag. FF does not trigger if you do not hit the person.