While the PlayStation Vita will support PSP games, it does not have a UMD drive. For this reason Sony came up with their UMD Passport program. Through this, you'll be able to register UMD games to get a discounted digital copy for your Vita on the PlayStation Network.
The list of UMD Passport games has gone live on the PlayStation Japan webpage. There's 262 games on the list as of now, which means a good bit of the PSP library is missing. While this list is in no way final, it's scary to see many publishers missing from the offerings. Note that none of Capcom, Konami, or Square Enix's titles are listed at all.
Before setting Sony HQ on fire remember that this list probably isn't final, and that it will likely grow. Also remember that the UMD Passport has not been announced for territories outside Japan.
I have a f*ckton of PSP UMDs. While I think that paying for a game twice is silly, at least there's some kind of program for me to get some use out of all of these games on the Vita. Let's hope that the full UMD library will be made available for the program, and that it comes to our shores.