MCV's website is reporting this morning that a VERY concrete source has stated that both the Playstation 4 and the next generation of the Xbox will be debuted this year at E3. MCV's editor has stated that while they can't reveal who their source is, but they have had a 100% accuracy rate with previous announcements of this type.
Reports are that both companies may not be able to launch their new consoles until 2014. This will give Nintendo a year ahead of the competition if they decide to launch their Wii U at the end of 2012 or Summer 2013.
While we may not have heard much from Microsoft about what their next console may entail, Sony has already stated that their systems are planned for 10 year cycles and this announcement would coincide with those plans.
Don't expect pricing or even an exact release date for either of these consoles for a while and may not be announced, even at E3. Stay tuned for more information as it develops.