From the BBC: http://www.bbc.co.uk/news/science-environment-22299403
More at link.
At the risk of sounding like a foam at the mouth Gaian - In 60 years we have so badly polluted low Earth orbit that it needs cleaning?
It's not so much about pollution as it is high velocity and a lack of atmosphere. The little stuff becomes like tiny missiles racing around; when it hits something the impact can be ferocious. The space shuttle windows were inspected after every flight to look for damage like this:
(http://orbitaldebris.jsc.nasa.gov/photogallery/gallarypage/sts7crack.jpg)
NASA has a webpage with some other images of the damage caused by micrometeorites in orbit - mostly due to stuff that got up there because of us: http://orbitaldebris.jsc.nasa.gov/photogallery/photogallery.html
It's almost a virtual certainty that space operations are going to leave debris so it's sort of inevitable that we'll need to figure out how to start clearing lanes through the stuff; otherwise we'll simply close ourselves in with a blanket of junk we can't get through.