Playstation 4 backwards compatibility?

Ok, so apparently there's a rumor going around that Sony is looking for a software engineer to make backwards compatibility (PS3, PS2, PS1 and suprisingly PSP games) for their next gen console, now I'm like WTF?! mainly because they said the PS3 will be around for 10 years, so why work on a PS4? I'm taking a guess that Sony has come across something that could rival the Wii and decided to start working on it now to speed things up for later (a controller mabye) which I could just say this is all another hoax, but it would make sense (especially with the progress being made in the brain wave controller department) and it'd be smart to throw in PSP on that list, it'd make the PS4's complete game library pretty large, consisting of thousands upon thousands of games.

My only thought is if Sony has stumbled upon something worth working on now, what is Nintendo doing? (Remember they have a list of investments and patents lying around for future use like, Floor Vision, Holograms, etc...)