  We report the detection of two planetary mass companions to the solar-type
star HD 155358. The two planets have orbital periods of 195.0 and 530.3 days,
with eccentricities of 0.11 and 0.18. The minimum masses for these planets are
0.89 and 0.50 Jupiter masses respectively. The orbits are close enough to each
other, and the planets are sufficiently massive, that the planets are
gravitationally interacting with each other, with their eccentricities and
arguments of periastron varying with periods of 2300--2700 years. While large
uncertainties remain in the orbital eccentricities, our orbital integration
calculations indicate that our derived orbits would be dynamically stable for
at least 10^8 years. With a metallicity [Fe/H] of -0.68, HD 155358 is tied with
the K1III giant planet host star HD 47536 for the lowest metallicity of any
planet host star yet found. Thus, a star with only 21% of the heavy-element
content of our Sun was still able to form a system of at least two Jovian-mass
planets and have their orbits evolve to semi-major axes of 0.6-1.2 AU.
