Seeing other solar systems
"With an instrument recently installed as part of the Keck Interferometer, they can make stars disappear almost completely from a telescope's view and reveal the close-in regions where planets may have formed. This fall, astronomers will continue integration and test of the instrument, called the "Nuller," which will contribute to NASA's search for planets around other stars."
http://www.spacedaily.com/news/telescopes-04zh.html
This nuller is apparently capable of blocking 99.9 of the star's light, I suppose over time they will be able to even improve on this.