This ought to be a no-brainer for any high-end Sony phone, but the company's new Xperia S flagship now has access to the PlayStation Store. The international phone didn't launch with the capability, which has been available to other Sony phones and tablets for some time, most notably the Sony Ericsson Xperia Play. Currently there's less than twenty original PlayStation games, almost all of which are considerably more expensive than most 3D games in the Google Play Store.
The Xperia S might not have a tablet-sized screen or integrated gaming controls, but with a 4.3-inch 720p screen, dual-core 1.5Ghz processor and a full gigabyte of RAM, it should be able to handle the emulated games (some of which are nearly twenty years old) with ease. Connecting an external controller will be a little tricky though - the Xperia S currently only runs Gingerbread, no without a little hacking it won't support game controls. Get comfy with virtual d-pads. An ICS update is planned for sometime this summer.
The app downloads from Sony's web service, which previously had been occupied with a placeholder link. You'll need to enable non-Google Play installations to get the PlayStation Store to install at first, but after that, it should be no trouble. The Xperia Ion, AT&T's American variant of the Xperia S, hasn't launched yet, but it should have the PlayStation Store installed by default when it does.