Charles Gibson signed off for the last time from the ABC News anchor desk tonight, bringing to a close his 34 years at the network with Friday's edition of ABC World News. Gibson, 66, called the job he's leaving "a labor of love." Since joining ABC in 1975, he served two stints as co-host of Good Morning America, was an anchor of the Primetime newsmagazine, and tackled numerous assignments as a correspondent. (More Charlie Gibson stories.)