A slightly more informative article, which references the paper published in nature (unfortunately, I couldn't find a copy of that that wasn't behind a paywall).

http://www.nature.com/news/2010/101124/full/news.2010.630.ht...

Note that the photons weren't made into matter. They were made into a Bose-Einstein Condensate, which is where all of the component particles share quantum properties and interact with the rest of the universe in "lockstep".

http://en.wikipedia.org/wiki/Bose%E2%80%93Einstein_condensat...