What Skittles just said. With PS3 the remote play was an afterthought, the PSVita was build with PS4 in mind. One can see it already by the special video/scaling chip that scales the PS4/full HD to a PSVita native resolution, without a hit on the PS4's hardware CPU/GPU.
On PS3 it can be harder to find out how it works, although I gotta say with Superfrog HD it works really flawlessly and easy to use. LBP2 was a bit harder.
PS4 will just be the handshake for both and go, anywhere you are. Think I even read that the PS4 to PSV stream is handled by the fast Gaikai network too. And yes, anywhere you have WiFi. Heck it will even work when you tether 3G/4G over your phone to the PSV wifi as long as its a good connection/fast enough. Check that you got a lot/unlimited data before you do so though...
The PS4 should have the disc in the slot though you want to play, or maybe Sony has a full installation mode for the BluRays this time so it is not needed. That is a wait and see, they might announce at Gamescom more about this!
<message edited by TheMART on Monday, August 12, 2013 3:02 AM>