yes, but onlythe 20GB and 60GB PS3's. The one's that are available now in stores are not backward compatible they only play ps3 games.
I suggest you buy the 60GB coz it has everything in it that other ps3's don't have. Coz 20 GB has no SD and MS slots and no Wifi, but still backward compatible and will play ps2 and ps1 games. While the new ones like 80GB and 160GB have wifi, SD and MS slots, but they don't play ps2 and ps1 games.
So just get the 60GB so you will have all the benefits out of a ps3. 60GB is a lot of space already anyway.
Note: you can only buy the 60GB online. Best would be on ebay. they sell new ones there too but too expensive coz it's hard to find now. but there are used and refurbished ones too that will cost less.