As of November 2011, the Earth Observing Handbook counts 109 active missions to study the Earth as a planet, with 112 more approved and planned for the future. Jason Davis provides an overview of key current and upcoming earth-observing missions.
The Mars Climate Sounder instrument provides routine nightside observations of atmospheric temperature and opacity that document the presence of rapidly evolving water ice cloud layers in the Martian tropics during the northern summer season.
There is a huge storm that's spreading across so much of Saturn that it's been readily visible even from Earth-based telescopes. Over the past couple of days a couple of new images of Saturn have appeared that show just how enormous the storm is today.