Confirmed by the National Zoo on their Facebook page, sometime before 11:00 pm EST, Mei Xiang had a cub. Have yet to be able to see the little cubby, as Mei had really built up her nest today, making it almost impossible to even see her in the den.
Congratulations to Mei, daddy Tian Tian and the National Zoo. These next couple of nights are critical, my prayers are with you Mei. You can watch Mei Live here: National Zoo panda cam or Daniel's multiple cam feeds.
Here is a video of Mei from the NZ live cams, you can't see the cub, but you can hear him/her.