The entire cast showed up... all twenty to thirty... I'm not actually going to count. Bryan Singer really showed me huh? They clarified the time travel saying that Kitty Pryde sends Wolverine back in time, but that it's just his consciousness meaning that Hugh is playing young and old Wolverine. They also played the first clip which hasn't leaked to the internet, but you can watch the press conference after the cast photos.

http://www.youtube.com/watch?v=cU_OJiBt2-8