  The CERN Axion Solar Telescope (CAST) experiment searches for solar axions by
the "helioscope" method. First results imply an upper limit on the axion-photon
coupling of g_a-gamma < 1.16 x 10^-10 GeV^-1 (95% CL) for m_a < 0.02 eV, in
this mass range superseding the previous energy-loss limit from globular
cluster stars. By virtue of a variable-pressure helium filling of the magnetic
transition region, CAST II will extend the sensitivity to axion masses up to
about 1 eV, for the first time testing realistic axion parameters in a
laboratory experiment. In this mass range axions would contribute a cosmic hot
dark matter component. New structure-formation limits imply that m_a < 1-2 eV.
For the particular case of hadronic axions with a standard axion-pion coupling,
the present-day cosmic axion density would be about 50 cm^-3 and the cosmic
mass limit is m_a < 1.05 eV (95% CL). We also comment on the axion
interpretation of the anomalous signature observed in the PVLAS experiment.
