  In the recent quantum-gravity literature there has been strong interest in
the possibility of Planck-scale departures from Lorentz symmetry, including
possible modifications of the energy/momentum dispersion relation. I stress
that a meaningful characterization of the progress of experimental bounds on
these Planck-scale effects requires the analysis of some reference test
theories, and I propose to focus on two ``minimal'' test theories, a
pure-kinematics test theory and an effective-field-theory-based test theory. I
illustrate some features of the phenomenology based on these test theories
considering some popular strategies for constraining Planck-scale effects, and
in particular I observe that sensitivities that are already in the Planck-scale
range for some parameters of the two test theories can be achieved using
observations of TeV photons from Blazars, both using the so-called ``gamma-ray
time-of-flight analyses'' and using the now robust evidence of absorption of
TeV photons. Instead the Crab-nebula synchrotron-radiation analyses, whose
preliminary sensitivity estimates raised high hopes, actually do not lead to
any bound on the parameters of the two ``minimal'' test theories. The
Crab-nebula synchrotron-radiation analyses do however constrain some possible
generalizations of one of the minimal test theories. As an example of
forthcoming data which could provide extremely stringent (beyond-Planckian)
limits on the two minimal test theories I consider the possibility of studies
of the GZK cutoff for cosmic-rays.
