  The OPERA neutrino experiment in the underground Gran Sasso Laboratory (LNGS)
was designed to perform the first detection of neutrino oscillations in direct
appearance mode in the $\nu_\mu\rightarrow\nu_\tau$ channel, the $\nu_\tau$
signature being the identification of the $\tau$-lepton created in its charged
current interaction. The hybrid apparatus consists of a large mass emulsion
film/lead target complemented by electronic detectors. It is placed in the high
energy long-baseline CERN to LNGS neutrino beam (CNGS) 730 km away from the
neutrino source. The observation of a first $\nu_\tau$ candidate event was
reported in 2010. In this paper, we present the status of the experiment based
on the analysis of the data taken during the first two years of operation
(2008-2009). The statistical significance of the one event observed so far is
then assessed.
