iv heard that the ps3 40gb have no ps2 graphic synthesizer chip or the ps2 emotion engine chip so i think its not possible, by the way i have the ps3 60gb and its really awesome as im playin ffxii..
its true that they removed the chip so you can't play ps2 games nativley. However if you look on the ps3 store you will see ps2 games that have been recoded to work on the ps3. I have often woundered though if they might develop something that you can just plug into the usb port and it would reintigrate the chips via usb.
the 40 gig ps3 was designed to play ps3 and psone games ONLY. There won't be an emulator or anything. People, before you buy a system, do the freakin' research!! You'd be better off with an 80 gig if you can't find any of the older models (20gb, 60gb).
To me that seems so damn sneaky - suddenly they release a ps3 without ps2 backwards compatibility and the average consumer doesn't even know. Talk about underhanded.