Quantum Gravity phenomenology: achievements and challenges
  Motivated by scenarios of quantum gravity, Planck-suppressed deviations from Lorentz invariance are expected at observable energies. Ultra-High-Energy Cosmic Rays, the most energetic particles ever observed in nature, yielded in the last two years strong constraints on deviations suppressed by $O(E^{2}/\Mpl^{2})$ and also, for the first time, on space-time foam, stringy inspired models of quantum gravity. We review the most important achievements and discuss future outlooks. 
Stefano Liberati (SISSA, Trieste and INFN, Trieste) and Luca Maccione   (DESY, Hamburg)
astro-ph.HE gr-qc hep-ph