I've found the official website, or YouTube Channel, of YouTube's Symphony orchestra which can be viewed here. They have a vide of the London Symphony Orchestra performing the short orchestral piece written by Tan Dun (warning, it is a bit schmaltzy), which as you may recall users from all over the world can download the instrumental parts, practice it, record it, and upload it onto YouTube wherein it will be judged.
They also have an impressive roster of 'YouTube Symphony Ambassadors,' first of which is Lang Lang, a superstar pianist. They also have a video of conductor Valery Gergiev talking about the project.
Another interesting thing to note are the four logos of Carnegie Hall, the London Symphony Orchestra, Michael Tilson Thomas, and Lang Lang on the front page, which to me are some of the most recognizable and famous names in classical music.
Browse around the site! There are loads of other interesting stuff to see.