Sources close to Edge have told the magazine that Ubisoft Montreal, as well as other developers have preliminary hardware based on the "intended specifications of Microsoft's Xbox 360 successor". Genuine dev kits on custom hardware are expected before this Christmas, which points to a 2012 retail release.
This would mean Microsoft would have to have something to show at E3 2012. Their goal, would be to keep the Wii U from gaining any ground in the next generation console war, and again get the jump on Sony.
Then again, Sony may be closer to a PS4 than previously thought. Edge also says that one Sony-owned developer has ceased work on the PS3 completely, and moved on to the successor's hardware.