In the news today:
"Astronomers use galactic magnifying lens to probe elusive dark energy."
http://www.physorg.com/news201427857.html
"A team of astronomers has used a massive galaxy cluster as a cosmic magnifying lens to study the nature of dark energy for the first time. When combined with existing techniques, their results significantly improve current measurements of the mass and energy content of the universe. The findings appear in the August 20 issue of the journal Science."
The rest of the article contains a general description of how gravitational lensing works and how scientists are using this phenomenon to determine the nature of 'darkness' (ie: Dark Matter & Dark Energy).
I'm sure we're likely to have some threads in the future on this 'little beauty'!
Cheers