quote: You don't need SM 4.0 to be a DX10 chip. SM4.0 is simply a shader model spec that is being released with it. It says in the article "supports DX9c, DX10 and SM3.0"
Other cards like the GeForce 6 series don't "support DX10 like every card released in the past few years" either. They are DX9. No card released to this day supports DX10. Though some DX10 games will have a roll-back feature to play on DX9 cards, the games then run in DX9 mode and are no longer DX10 games. The next-gen games supporting DX10 can run on older DX9 cards in DX9, DX10 doesn't run on DX9 hardware. Get it straight.