The SAS and Leet models have finally been released for CS: Source! The update will be applied automatically when your Steam client is restarted. The specific changes include:

Counter-Strike: Source Updates

• Added Leet and SAS player models
  
• Fixed players being able to run up very steep slopes for short distances
  
• Fixed low-violence models not animating properly
  
• Improved player ragdolls

News Source: Steam News