If you don't want to pay $32 to read the full article on Nature's website, you can read the arxiv version here: http://front.math.ucdavis.edu/1207.0809 Bob Baillie --- Warren Smith wrote:

Dark matter filament found, scientists say Astrophysicists say they have discovered one strand of the long-elusive dark matter filaments, thought to connect galaxies and help shape the universe.

That was the headline of this LA times article http://www.latimes.com/news/science/la-sci-dark-matter-filament-20120705,0,6...

http://www.nature.com/news/dark-matter-s-tendrils-revealed-1.10951

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11224.html

The filament of dark matter connects two galaxies; it is 5.8*10^7 light years long and 3*10^6 light years in diameter. It has mass between (6.5 and 9.8)*10^13 solar masses.

In contrast the Milky Way has 1.25*10^12 solar masses and is 10^5 light years in diameter.

So for those who want to believe there is no such thing as dark matter, since really there is some other theory of gravity which explains the gravitational effects attributed to dark matter... this would seem to present a serious challenge?