  We present radial-velocity sequences acquired during three transits of the
exoplanet HD 189733b and one transit of the CoRoT-3b. We applied a combined
Markov-Chain Monte Carlo analysis of spectroscopic and photometric data on
these stars, to determine a full set of system parameters including the project
spin-orbit misalignement angle of HD 189733b to an unprecedented precision via
the Rossiter-McLaughlin effect: beta = 0.85 degrees (+0.32 -0.28) . This small
but non-zero inclination of the planetary orbit is important to understand the
origin of the system. On CoRoT-3b, results seem to point towards a non-zero
inclination as well with beta = 37.6 degrees (+10.0 -22.3), but this remains
marginal. Systematic effects due to non-gaussian cross-correlation functions
appear to be the main cause of significant residuals that prevent an accurate
determination of the projected stellar rotation velocity V sin(I) for both
stars.
