PS4 launch details were around when the PS3 launch was out, it just a little more realistic these days as for what you can expect, there are real details just rumours and a lot of hearsay... I doubt they move away from the blu-ray format since it can hold far more than 50GB (DL-BluRay Disc) these days, last i heard they had the capacity up to 400GBs which is alot.
As for a release date, 2014 is most likely, the PS3 still has alot of feature still left ot come out, Xbox too, so the we still going to see much more added value before a new consloe is released. If you want cutting egde for now move to PC gaming... really thats where gaming began and its eventual death bed.