Developer Yosh (a.k.a. wth) recently found another savegame exploit on a PSP game, which he confirmed to work on the vita (video
below).

It is also my understanding that hes been making good progress on porting HBL to this exploit on the PS Vita. The usefulness of this will mostly depend on what happens after the first release of VHBL, a homebrew Loader for the PS Vita, scheduled for soon.