If you recall, part of Sony's most recent media blitz was the PlayStation Suite, which allows access to older titles in Sony's console history (and theoretically pushing other, newer titles in some form) on both the NGP and Android market. The initial lineup seems to mostly be PSOne classics, which we can already grab from the PSN.
The European Sony PlayStation blog recently had a bit of a break down on what that process entails. First, a disc has to be found, data taken, and it has to be tested. Naturally, there are some times when egregious bugs sneak into those warm, comfortably nostalgic memories and ruin the entire experience. Considering that many studios don't exist anymore, or don't have the same tools as they once did, fixing those can be problematic. The good news it that these bugs are sometimes just the result of an emulator not working well with the data, in which case later emulators may fix the bug (and possibly introduce new ones?). That's merely the first step, however, and can take quite a while in its own right.
The second step is to check out the licenses involved with the game. In what seems, in retrospect, to be either a short-sighted or business-savvy move (depending on where you stand in that food chain), the licensing for a product typically only extends to the product's expected life expectancy. As games are a relatively new medium, and as the threat of failing hardware becomes more prevalent, the thought of reintroducing certain games under official channels of emulation weren't forefront on anyone's mind. Which does beg the larger concern of how we're preparing for a future of preserving games and our access to them. Then again, Sony's lack of backwards compatibility on later models of the PS3 doesn't give one much hope.
Then there's the ever-present question. Why do some games release on the PSOne classics in Japan, but not North America or the PAL regions? Licensing again rears its mercantile-fingery head, as each region may have different licensing arrangements based on who owns rights in what region (for games, movies, products featured in the game, etc.), and all that good stuff. The other issue? The game may encounter bugs in the PAL version that weren't present in the NTSC. There's also the fact that, when possible, Sony is trying to make sure every game has multi-language support. Some games have been released with their English-only tracks, but that won't work with all games.
What this means is that there are some games which have been in the works since 2007. It also means they further gave us some hints as to what games are on their way: Tombi and Wild Arms for the PAL region (the latter of which is already in the NA store).
Which brings the question. What other games would you like to see available from the PSOne? Seeing as I never had the system itself, my library from it is woefully lacking, and many of those games are now far more expensive than I am willing to pay.