Put Start the Party or Kung Fu Rider into your PS3 and hop over to the What's New menu, where you'll find the option to install demos to your HDD. Which demos are included? A demo of either Start the Party or Kung Fu Rider, naturally depending on which disc you bought, as well as trials of Sports Champions, EyePet: Move Edition, Tumble, TV Superstars and echochrome ii.
If you feel like saving your bandwidth from downloading these demos, you might want to consider picking up Start the Party or Kung Fu Rider for immediate access to these demos. It's possible other titles will contain demos too, so stay tuned for more information.