Came across this info that is reportedly from a very reliable source, but I haven't heard more since the article went up in March. But if this is real and the update comes by or before E3, I may go get a PS4 earlier than I originally planned! I've got some PS2 games my boys like to play, and the old PS2 is having more and more trouble loading up content.
http://www.escapistmagazine.com/news/view/133240-Sony-May-Add-Backward-Compatibility-to-the-PS4
http://www.escapistmagazine.com/news/view/133240-Sony-May-Add-Backward-Compatibility-to-the-PS4