writes "Could we detect a huge volcanic eruption on an exoplanet 30 light-years from Earth? Possibly, say scientists from the Harvard-Smithsonian Center for Astrophysics. What's more, there may be an opportunity for us to spot the ashy pollution ejected into the exoplanetary atmosphere when NASA's James Webb Space Telescope is launched in 2014. According to Discovery News, this would be a huge discovery if an Earth-like world was found to have active volcanoes: 'A geologically active terrestrial planet may be more suitable for life. It recycles crust, unleashes greenhouse gasses, opens new environmental niches, and generally provides a dynamic environment for advantageous life forms.'"
According to a related story at the BBC, we should soon be able to detect the presence of oceans on distant worlds as well
. The JWST will be able to resolve the reflection of light off an ocean's surface from 20-30 light-years away.