At E3 in 2009 (and 2010), Microsoft's Kinect camera was promising, but also glitchy. At E3 2011, it looked more responsive. And there's a reason for that.
Xbox senior product manager David Dennis has said in an interview with Eurogamer "I think like we showed at E3, like Kudo showed with Kinect Fun Labs – a lot of that tech is the advancements we've made in the accuracy, the tracking... being able to show finger tracking in the sparkles demo he did."
"You saw too with Ubisoft's gunsmith demo [for Ghost Recon: Future Soldier] he was using his hand to fire in the firing range mode. I think that's the kind of thing we're going to continue to iterate on."
While Dennis didn't go into the technical specifics of just how those improvements came about, he did say that, just as Kinect has been improved once via updates, it can be tinkered with again and again in the future.
Kinect more accurate now than at launch [Eurogamer]