Opera neutrino oscillation experiment: On the way to ν_τ observation

The hypothesis of neutrino flavour changing in weak interaction representation via oscillations is confirmed by several experiments, all based on the observation of the disappearance of a given neutrino flavour. The direct appearance of a flavour different from the initial one, was never observed so far. OPERA is the first long baseline neutrino oscillation experiment employing nuclear emulsions for the direct observation of tau neutrinos in the CERN to Gran Sasso muon neutrino beam. At present the experiment is in the data taking phase. The number of detected neutrino interactions have exceeded one thousand. Experiment status and a summary of results from 2007 and 2008 runs is presented in this paper.