I haven't yet. I honestly doubt I will before we pull out / reduce ops / whatever the heck happens in 2011. It depends upon what trade you are, how qualified you are, and the requirements in Afghanistan. Or wherever else the Canadian Armed Forces is mandated to conduct operations, now and in the future.
If you join the reg force, you will go where you are told, when you are told. You may be part of a unit that is given orders to pack up, or you yourself may be selected to go. In some cases, it may be decided that you are more useful in country than on operations. In other cases, you may be needed to support said operations. The two main jobs of the military are conducting operations, and preparing for future operations. This includes stuff like the procurement / development of new equipment, and training of new personnel. Some people may even spend their entire career in this role. Some other people may spend the bulk of their career on operations, or at least posted to an operation unit. Both roles are needed.