Talk about a being a great friend. Justin Timberlake
was the surprise guest during his pal Timbaland's performance at last night's launch of the United Nations Foundation's new mobile initiative, mPowering Action, at the Conga Room in downtown Los Angeles. J.T. joined Timbaland on stage to perform their hit "Carry Out" for an enthusiastic crowd of twentysomethings, including hottie Kellan Lutz
, his Twilight costar Nikki Reed
and her husband, Paul McDonald
. Also in the audience were Timberlake's fellow 'NSync member Joey Fatone
and his wife Kelly. (Fatone told me he and Timberlake talked a couple of weeks ago for their birthdays, which are just three days apart.) Dressed in a...