The Vita is almost upon us, packing enough raw power to emulate some of the best titles of the previous generation... if not this one. However, Sony has announced that they have no plans to bring a selection of PS2 and PS3 games to their new handheld in the forseeable future, instead suggesting that players can enjoy entirely new games as well as supported PSP downloads and PSone classics.
"Users can play supported digital PSP titles and supported minis. In regard to PSone classics titles, we will announce further details when they are ready."
"PlayStation does not have plans to make PS Vita compatible with PS3 or PS2 titles at this point." - PS Vita FAQ
The words "missing" and "trick" come to mind.