I have to agree with JustScott on this one. To add, for me the question becomes, 'What are my motives for masturbating?' I don't believe Jesus ever specifically addressed this issue, and the statement by Christ that lusting after another in one's heart, isn't a direct reference to masturbation, but to our sin.

Let me explain, if our motive is to think lustful thoughts, and the outcome is masturbation, masturbation isn't the sin, the lustful thoughts are.

God gave us the gift of sex for the purpose of giving pleasure to another, not just for ourselves. But then at some point, the issue needs to be addressed as what to do when sexual pleasure within the boundries of a God sanctioned relationship is interrupted due to say illness, distance, etc. If someone's urge compells them to act, which would be better: Masturbating, or committing adultry?

My 2 shekels worth.

"I'm entitled to my opinion...even if it's wrong."