Well as of right now, the PS3 is a blu ray player, but with so much more. If you just want to use it as a standalone blu ray player, and play some PS3 games, watch HD movies, pictures, nmusic, intrernet etc, get a PS3.
But if you're not that much into gaming and dont have alot of memory cards like the SD and such, play PS2 games, and use it for computing, get a 40gb PS3. A 40gb only has 2 USB ports, no PS2 backwards compatibility, and no memory card readers. But all PS3 have Blu-Ray.
If you want to spend that extra 100, get an 80gb PS3, it has PS2 backwards compatibility, 4 USB ports, and memory card readers. This is the same as the 60gb, except more GB and less PS2 playback.
A regular Blu-Ray player costs about what? 1 grand? And it can only play blu ray movies. While as a PS3 is a blu-ray player, AND it can play games, play videos, pictures, music, friends, internet, demos etc. You will find it similar like the XBOX 360â„¢, except with blu-ray, free internet, and much more.