Wave is a Content Distribution System.

As end-user you can:

• Download product demos, view screenshots, videos
  
• Buy and download products you like via PayPal
  
• Update your installed products with one click
  
• See what your friends are playing, join the server they are playing on (if its a mulitplayer game)
  

As developer you can:

• Distribute your products easily (you don't have to search for a publisher)
  
• Advertise your products (demos, videos, etc.)
  
• If many people are using Wave, but don't know your company, you will get attention through Wave
  
• Protect your products against illegal use
  
• Update your product easily
  
• Don't waste money for distributing your product in stores
  
• Your game musn't be rated (ESRB, USK, etc.)
  

Indeed it is similiar to Steam, but Wave is designed for Indi-Developers.

Best Regards