According to the Planetary Habitability Laboratory's recently released Periodic table of exoplanets, 16 warm Neptunes and 96 warm Jovians lay within their star's habitable zone. If they managed to capture rocky Earth-sized moons on their journey inward, such moons would be able to hold liquid water, and be potential wells of life.
This includes Kepler and other exoplanet data current as of January 5, 2012.

CREDIT: PHL