I don't think a cover system like that would work well in first person, and I don't like the idea of being forced into third person (looking at you, Deus Ex Human Revolution...).
there are tons of ways a cover system could work in first-person. i've conceptualized a number of them for a game like STALKER.
a STEALTH cover system, though, i don't think so. Thief: Deadly Shadows had the ability to hug walls, which was kind of neat.
but pretty much cover systems are useless unless everybody's got guns.