The PlayStation 4's existence has been outed, subsequently confirming the unannounced console is currently in development.
Frederick Umminger’s LinkedIn profile (via Superannuation) states he worked on "Maintained voice chat library for PlayStation 4″ since June 2010 to the present day. He's been working as a software engineering manager at Sony Computer Entertainment America.
The revelation may be surprising to many due to Sony's strong stance of supporting the PlayStation 3 within its projected 10 year life cycle. Next year, that life cycle would see the console becoming seven years old.
Sony has also gone on the record by stating, as was the case with Microsoft regarding the Xbox 360 successor, that a follow up to the PlayStation 3 won't be revealed at this year's E3. That said, there's been an increased amount of speculation pertaining to the PS4 since 2011. Countless sources have tipped the platform and the Xbox 720 to launch by the end of 2013.