people rap straight down el cap every year. not sure what kind of gear they use but you can google it. its like thing you can (or could) pay to do. as far as rapping half dome people do portions of it all the time. its like 20 something pitches and i think all belays are bolted. people have rappelled down part or all of snake dike and even the cables too (instead of using the
cables) but the person in the original post probably meant she just used the cables to get down.
as far as rapping one shot straight down the face like they do on el cap, it would leave the person on the 'death slabs.' theyd have
to go down from there or climb the social trail below the face to the subdome
area. could be fun i guess...i think id rather pay someone to drag me up the face rather than pay someone to haul a rope up there, hike up and slide down it.