  The analysis of the submm anisotropies that will be mapped by the forthcoming
MAP and PLANCK satellites requires careful foreground subtraction before
measuring CMB fluctuations. Among these, the foreground due to IR/submm thermal
radiation from dusty sources was poorly known until recent observational
breakthroughs began unveiling the properties of these objects. We hereafter
briefly review the observational evidence for a strong evolution of IR/submm
sources with respect to the local universe explored by IRAS. We present the
basic principles of a new modeling effort where consistent spectral energy
distributions of galaxies are implemented into the paradigm of hierarchical
clustering with the fashionable semi-analytic approach. This model provides us
with specific predictions in IR/submm wavebands, that seem to reproduce the
current status of the observations and help assessing the capabilities of
forthcoming instruments to pursue the exploration of the deep universe at
IR/submm wavelengths. Finally, the ability of the PLANCK High Frequency
Instrument all-sky survey to produce a catalogue of dusty sources at submm
wavelengths is briefly described.
