In Japan, Sony had a program called UMD Passport where users could get discounted digital versions of PSP games so they could play them on Vita. Starting on September 17 and until the end of the year, the entire UMD Passport catalog will be available as Free Play games for PlayStation Plus members.
This gives Vita owners access to 250 games including Monster Hunter Freedom Unite, Final Fantasy Type-0, Ys Seven, The Legend of Heroes: Trails in the Sky, and Monster Hunter Portable 3rd.