I like how the Essential Rogue preview opens up--yet a-fucking-gain--with a disclaimer about how Essentials isn't a new edition, replacing the original core rulebooks, or is in any way incompatible with 4E. Of course, I still expect to see forum-wankers clamoring to the contrary (which is why I don't like the forums).
The featured rogue build is a thief. Sneak Attack is still there and works like you'd expect (edit: Shazbot pointed out that it works on a turn-by-turn basis, instead of round-by-round, and you can do it with shortbows to boot), but backstab makes a return as an encounter exploit that you can activate against a creature granting combat advantage to you and within 5 squares as a free action, giving you a +3 power bonus to the attack roll and an extra d6 damage to boot. Other class features include Weapon Finesse, First Strike, Skill Mastery, Cunning Escape, and Combat Readiness, though none of them are explained.
Unlike the various "essential fighter" builds, the essential rogue doesn't modify her basic attacks with stances, instead having to burn move actions to both let her move and add on a kicker effect to her basic attacks. Ambush strike lets you move your speed, and until the end of your next turn causes all enemies within 5 squares to grant combat advantage to you. Feinting trick, on the other hand, let's you move your speed and let's you add your Charisma modifier to damage so long as the target doesn't grant combat advantage.