The latest tease of Xbox 720, as it is widely known as on the web at this point, comes from the financial publication Bloomberg. Their "people familiar with the company's [Microsoft] plans" confirm that Microsoft will release the next Xbox in time for Thanksgiving and Christmas sales in 2013. This would indicated an early-to-mid November time frame for the console's release, the same time of year Xbox and Xbox 360 were released.
These same sources are unsure at this time whether Microsoft will unveil the next Xbox at E3 in June 2013, or if a separate industry event will be held ala Apple. Xbox 360 was unveiled at E3 in a splashy announcement and expectations are Xbox 720 will follow a similar roadmap to the public's eye.
Nintendo released their next generation gaming console, Wii U, less than two weeks ago. It was originally revealed at E3 2011, leaving a year and a half between the first unveiling and release for development to unfold. Xbox 720 should be near its retail design and have a launch lineup partially in place by the time members of the media get their hands on it for the first time.
Odds are favorable that Microsoft will be battling with Sony next holiday season with the likely introduction of the Playstation 3 successor. Nintendo's Wii U will be "old news" then, but the company can easily draw attention to itself with a new 3D Mario, Zelda or Super Smash Bros. Brawl title that gamers are clamoring for.