Sony plans to get the PS4, A.K.A. "Orbis", onto store shelves before the next Xbox, says VG247. According to recent rumors, both consoles are expected to launch some time around the 2013 holiday season.
The Xbox 360 was released in November 2005. The PS3 didn't make its retail debut in the US until November 2006. Sony seems to be incredibly concerned with making sure they're first out of the gate this time. Sony is apparently "confident" they'll have get their console out first.
“Sony are completely in the belief that they have the jump on Microsoft this time,” according to the site's anonymous source. “You should be watching the timing of next year’s E3 keynotes, and who’s going to go first.”
A small circle of top-tier third-party developers, including Ubisoft, have apparently already been brought into the loop regarding the new console's development. Sony will supposedly expand that circle over time, beginning with planned developer reveals in May and June, to all participating studios by the end of 2012.