I am not entirely knowledgeable about this, but I will give it a shot until someone with real knowledge comes.
With emulation from the consoles, it has to emulate code for each peice of the hardware. It will have to emulate the PS3s video card, emulate the processors, etc. which will not be possible... probably never unless we get some beast of a computer and have a dedicated team to program it.
Just look at the PS2 emulation, It is pretty much recommended to have a dualcore 4 GHZ processor to run all the games supported effectively. This is not even counting changing the resolution to 1080p which some games raped my old 8800GT.
Though this could be narrowed down to unoptimized coding, but from everything they have done to make it possible... impressive. =)
Emulation from what I know is not against the law, just providing software/bios from what I know is... *shrug* ;p
emulators are not illegal. only the copying the bios is illegal if you dont own the machine.
as for a ps3 emulator there isnt 1 and considering you need a system like mine just to run a ps2 1 at reasonable frames per. its unlikely you could get a ps3 emulator to work on pc till 2-3 years time on hardware that doesn't exist yet.
yea well... answer is there isint any. even ps2 emulator is laggy and wont work on all games. ps1 emulator has problems and how old are they?... so nope there aint any ps3 emulators. and i guess after 5-10 years they make one if they get enought powerful and cheap computer parts to run ps3 games.
but hey you can look ps3 store with your computer ... or buy ps3, external usb hd and hack it. (ps3hacks.com)