  Fewer giants planets are found around M dwarfs than around more massive
stars, and this dependence of planetary characteristics on the mass of the
central star is an important observational diagnostic of planetary formation
theories. In part to improve on those statistics, we are monitoring the radial
velocities of nearby M dwarfs with the HARPS spectrograph on the ESO 3.6 m
telescope. We present here the detection of giant planets around two nearby M0
dwarfs: planets, with minimum masses of respectively 5 Jupiter masses and 1
Saturn mass, orbit around Gl 676A and HIP 12961. The latter is, by over a
factor of two, the most massive planet found by radial velocity monitoring of
an M dwarf, but its being found around an early M-dwarf is in approximate line
with the upper envelope of the planetary vs stellar mass diagram. HIP 12961
([Fe/H]=-0.07) is slightly more metal-rich than the average solar neighborhood
([Fe/H]=-0.17), and Gl 676A ([Fe/H=0.18) significantly so. The two stars
together therefore reinforce the growing trend for giant planets being more
frequent around more metal-rich M dwarfs, and the 5~Jupiter mass Gl 676Ab being
found around a metal-rich star is consistent with the expectation that the most
massive planets preferentially form in disks with large condensate masses.
