SNKPlaymore has just announced the release date for SNK Arcade Classics 0 (zero) as the 21st April in Japan, and will be released for the PSP. I assume as with the previous collections these would make their way also to the West in due time, but as of yet i cannot find a Western release date yet.
As the title of the collection hints at, these will be a collection of their oldest games (before MVS/AES) and will have games such as Athena, Psycho Soldiers, Street Smart, and Ikari Warriors.
One thing i am a bit concerned with though is how well these will be ported to the PSP, i have read alot of negative reviews about SNKP's other collection releases and personally though SNK Arcade Classics Vol.1 on the PS2 wasn't ported very well.
Hopefully if the port is decent it should be good to play some of these old titles.
Check out the official website here for more details and a list of games which will be on this collection.