Here we are again and only a short time after the 1st Rants & Raves post.
Anyway... Keeping in line with the last rant about TLoS, it would seem that there's an equal amount of [expletive delete] that can't grasp the new cover saves. So again here I am posting actual rulebook excerpts to try and clear things up.
"When any part of the target model’s body (as defined previously by the LoS rules) is obscured from the point of view of the firer, the target model is in cover. This is intentionally generous, and it represents the fact that the warrior, unlike the model, will be actively trying to take cover (as well as the smoke, explosions and flying debris that are mercifully absent from our tabletop battlefields)." "If a target is partially hidden from the firer’s view by other models, it receives a 4+ cover save in the same way as if it was behind terrain."
Intervening models includes ALL models, friend and foe alike.
Update: There's a lot of asshats out there trying to abuse the new cover save rules vs. intervening models. They're trying to grant a symbiotic cover save amongst two units in a staggered formation (See Image). This is a sticky situation because it works, but is generally considered to be an underhanded or "beardy" tactic. In the image we see a SM (Spacemarine) unit firing into a staggered formation of two Ork units.
From the SM position both Ork units will receive a cover save, because even though there are no intervening models to fire through to hit unit 1 the majority of it is behind unit 2 granting it a 4+ cover save. In regards to unit 2 the cover save rules specifically state that "If a model fires through the gaps between models in an intervening unit, the target is in cover".