A few days ago PS3 hacker Flatz dumped everything he'd been able to decrypt about PS2 Classics for the rest of the scene to take a look at, citing a lack of free time to work on it any further. Just days later, the folks over at PS3hax.net have come up with a guide for getting PS2 ISOs set up in conjunction with a PS2 Classics template package for playability on any PS3 running a 4.20 or higher CFW, fat or slim.
Obviously compatibility's not going to be perfect (it probably won't work with multi-disc games, either), and I don't currently have a system I can test with, but even the basic premise is a huge step forward from what's been available for non-backwards-compatible models.
I apologize if this has already been posted, or if some of the info is wrong. Truth of the matter is I saw the news and kind of skimmed the rest, partly out of excitement and partly out of knowledge that it'd mostly be useless to me until I got my hands on another hackable system.