The explode modifier works together with a particle system to split a mesh into pieces and have the pieces follow particles. The particle system that will be used must be position before the explode modifier in the stack.

• Vertex Group: defines which parts of the mesh explode.
  
  • Clean vertex group edges.
• Refresh: recalculate faces assigned to particles.
• Split Edges: split edges for nicer shrapnel.
• Unborn, Alive, Dead: settings to show or hide unborn, alive or dead particle pieces.

An example .blend file is available.