Alli Rainey has a great post on prAna's blog about dealing with fear. Rainey, a 5.14 climber and Harvard grad, writes that she's struggled with a serious, often-crippling fear of heights since she started climbing in 1992. A troublesome problem for a sponsored climber, as you might imagine.
Rainey's solution has been to slowly work her way through her fear instead of trying to fight it off. While she says her fear is "still very much alive," she's dealt with it through a process that she describes as "systematic desensitization/exposure therapy," edging her way through exposed approaches and up steep routes until the visceral terror of the experience began to fade into dull discomfort.
The post should make for good reading for anyone who has been kept away from climbing by a phobia of heights. I think that more climbers than not have to face a fear of heights or falling at some point, and learning to deal is what sets some of the most successful ones apart.
Check out the above video of Rainey on Galactic Emperor in Ten Sleep, Wyoming to see how far she's come.