Who knew?
A cannabis-derived drug called Sativex, meant to help mutliple sclerosis patients manage pain, is already legal in Canada. The drug is administered orally, in liquid form, and has already become informally known as "liquid pot."
Sativex has a long, informative Wikipedia entry if you're curious about the drug...
Evidently it's also been approved for upcoming FDA trials, although one would never know for all the publicity this has received...
Finally, if you're interested in Sativex's effect on the American Drug war and the medical marijuana battles in California and beyond, then you might check out Reason Magazine's piece "If Sativex Works, So Does Pot."