I was discovering this last night with my Rogue 2. A big fighter came on the scene and our back line was badly exposed with the Dragonborn Paladin 2 and Dwarf Fighter 2 surround elsewhere.Indeed, warlords of any stripe are ideal buddies for rogues.
We were already mildly occupied in the back line when the Fighter appeared on the scene, and it was clear that he was a significant threat. The Tiefling Warlord 2 went to strike an opponent we had engaged and casually asked if I wanted a free shift (through some Wolf Pack Tactics power or similar) - I didn't even know he could do that for me! I said sure, and positioned my self one square closer to the Fighter - nobody could work out why I would do that!
The Fighter closed on my Rogue and engaged and then I hit him with my Positioning Strike encounter power to slide him down a 30ft well in the centre of the room - which not only damaged him but took him out of the play for a few rounds while we regained the upper hand.
From that point on, the Warlord and I were working as a team to deal with anything that penetrated the front line, with the Warlord shifting my Rogue around for better tactical position.