JOEL - I know of no recent formal statements from the Church against the use of medical marijuana; only general statements such as the following one against things containing habit-forming ingredients:

"the leaders of the Church have advised, and do now specifically advise, against the use of any drink containing harmful habit-forming drugs under circumstances that would result in the acquiring of the habit."
(1971 letter from Elder Joseph Anderson Secretary to the First Presidency)

The key point as far as the Word of Wisdom is concerned is to avoid becoming addicted to any drug. Aside from some other harmful effects, Marijuana can be very addictive for about 10 to 14% of those who decide to use it. See this site.

There are other potentially addictive drugs that are prescribed by doctors and used by LDS members all the time. Many might argue that Marijuana would be included with these as being safe if used under the direction of their physician.
The problem is that those other drugs are legal while there are federal laws against the use of marijuana for any purpose. One can be arrested by federal officials for posession of it, even though many states have their own laws that allow it under certain circumstances for medical use.
The question is, would it be proper for an active LDS member to go against federal laws, even if it's for medical reasons? This would be something that would have to be decided between the member and God.