Jupiter and the 3 moons January 4, 2011 18:24 EST, Venus and Saturn shot a few hours later just before dawn.
All to the same scale, shot with a D300 500 f/4 AFS TC17-17E-II at 850mm on a Questar 7 motorized equatorial fork mount.
Exposures, with apparent diameter of the planets, and Saturn's major ring axis:
Jupiter's Moons: f/8 10s ISO 400
Jupiter: f/11 1/50s ISO 200 (38")
Venus: f/8 1/250s ISO 400 (26")
Saturn: f/8 1/10s ISO 200 (17" (disk) and 39" (rings))