ATI Catalyst drivers have a problem
 

So, to show it is mostly there, ATI coined the term SM2.0b, something that encompasses most of the SM3.0 functionality. When a game is written for SM2.0b, it has most of the advantages of a SM3.0 program, both in looks and in speed. ATI gets the the speed, features and lower die sizes, win/win/win.

There are two problems here though. The first is that most developers won't write a special code path for a single card. Usually, it takes undue attention from a graphics card company, meaning coding help, man hours, and money. For marquee games, ATI sends out the developer hit squad and makes the game shine on its cards. Far Cry was a perfect example of this, Nvidia waved the SM3.0 flag, and no sooner had they done that than a SM2.0b patch was announced. Magic.

http://www.theinquirer.net/?article=18119