I'm in agreement with The Grackle actually, I think passive perception is the intention in the rules. (One of the viewpoints I've changed on.) Just to avoid a stupid amount of dice rolling, if anything.
And just to be clear, I use the phrase Stealth As Intended™ to mean, "WotC intended for stealth to be usable during combat to grant combat advantage." When I spoke to a CSR on the phone, he put me on hold and went to ask a rules guy. While they give varying answers on the minutia of the check, they all consistently stated that it's intended to grant combat advantage, and only requires normal cover/concealment, or a successful bluff. It's just a lot quicker to type Stealth As Intended™, and funnier, in my opinion. Speaking of funny, I give you:
The Bleu RAWja
Halfling Rogue (1)
STR 11 | CON 10 | DEX 20 | INT 8 | WIS 10 | CHA 16
AC 17 (19 vs OA) | FORT 10 | REF 17 | WILL 13
Backstabber (+2d8 sneak attack)
Stealth +12
Sly Flourish +8 vs AC (shuriken) 1d6+8
Equipment: Leather armor, a dagger, and so many shurikens... well... too many.
Hell. Yes. This is my Stealth As Intended™ rogue.

He wears an red velvet cape and a jeweled turban with a feather.