i dont really follow the ps vita scene much at all, and from what i understood it was only the PSP emulator side of it that is/was ever semi hacked. now the PSP was hacked so early on its life cycle due to sony rushing it out to compete with the nintendo ds and thus left debugging stuff in the 1.00 original firmware. sony learned from that major mistake, and also learned from the ps3's security features semi failures. so i see the ps vita being another PS3 style scene were it will take years before we see anything remotely close to were the ps3 is now in terms of being opened/hacked for unsigned code that isnt just PSP mode related.
i personally dont like the vita, hope it never takes off, and sony never makes another handheld console again.
i did enjoy the PSP back in the dark alex haydays but most PSP games sucked IMO. i doubt the vita will ever be anything close to what the psp was in its prime. id like to be proved wrong tho.