The PlayStation Vita will allow you to play every single PS3 game via remote play, a feature that will be added via a firmware update further down the line. Eurogamer, who don't cite a source, say that the only downside to this will be that the games will show at 480×272 – the PSPs max resolution – instead of Vita's max capabitity 960×544, presumably because the remote play feature was created with the PSP in mind.
Outside of the obvious, being able to play PS3 games on the move, you'll also be able to play specially created co-op modes that will use both consoles. So long as it works well and is well supported, this Wii U influenced feature may stop some users from making the switch to Nintendo's next console.
By no means confirmed, Sony refused to comment, but a very interesting piece of news if true.