  We report a new determination of the faint end of the galaxy luminosity
function in the nearby clusters Virgo and Abell 2199 using data from SDSS and
the Hectospec multifiber spectrograph on the MMT. The luminosity function of
A2199 is consistent with a single Schechter function to M_r=-15.6 + 5 log h_70
with a faint-end slope of alpha=-1.13+/-0.07. The LF in Virgo extends to
M_r=-13.5= M^*+8 and has a slope of alpha=-1.28+/-0.06. The red sequence of
cluster members is prominent in both clusters, and almost no cluster galaxies
are redder than this sequence. We show that selecting objects on the red
sequence and blueward produces a steeply rising faint-end. A large fraction of
photometric red-sequence galaxies lie behind the cluster. We compare our
results to previous estimates and find poor agreement with estimates based on
statistical background subtraction but good agreement with estimates based on
photometric membership classifications (e.g., colors, morphology, surface
brightness). We conclude that spectroscopic data are critical for estimating
the faint end of the luminosity function in clusters. The faint-end slope we
find is consistent with values found for field galaxies, weakening any argument
for environmental evolution in the relative abundance of dwarf galaxies.
However, dwarf galaxies in clusters are significantly redder than field
galaxies of similar luminosity or mass, indicating that star formation
processes in dwarfs do depend on environment.
