According to a Firing Squad interview with Sony's director of external development, John Hight, classic arcade titles should be on the way to the PlayStation Store. "Sony's third-party publishers will undoubtedly provide updated versions of classic arcade games," he said.
We learned yesterday that PS3 arcade titles will have a larger size limit than the games in the Xbox Live Marketplace; 500MB compared to 50MB. Therefore, when Hight said the system will be able to "accomodate even bigger games and a lot of them," this is likely a more appealing scenario to publishers than the Marketplace situation.
As of yet, however, no third-party publishers have announced any plans for downloadable arcade titles on the PS3.