In reply to JossGuyer:
I think this is rather a complex question and this will therefore not contain an answer.
From my experience its seems to that climbing (like many other activities) facilitates and indeed insists upon a meditative and focused mind state and to this extent deals in the short term with stress.
However it is also my experience that its possible to access this mind state as a displacement behaviour rather than addressing other stressors - in this instance I suspect I'd simply be masking the effects of long term stressors by voluntarily adopting a more acute one. Its also possible for climbing ( and other activities) to become disproportionately important in terms of one's self image and self esteem and thus become a source of dissatisfaction in themselves.
This might seem pessimistic, so I should emphasise that climbing is an excellent mechanism for achieving "time out of mind" - the more difficult question is why that goal is to be desired?