It happened last night in London! 

There were recent rumblings that David Gilmour would join Roger Waters on stage when Roger brought his 30th Anniversary Wall Tour to Europe. Nobody knew at which show it would happen, but it happened last night at the o2.

Not only did David hop on stage, Nick Mason joined in as well. They performed "Comfortably Numb" and "Outside the Wall".

There are no plans for any future reunions, but a full reunion will never be possible as Richard Wright passed away in 2008. "Comfortably Numb" was the last song the foursome ever performed together at Live 8 in 2005. Here is the full Pink Floyd set from Live 8.