This article  (free access, at least for now) summarizes the
current status of five oral drugs currently in clinical trial for MS:
teriflunomide, laquinomod, fingolimod, BG00012, and cladribine.
Results of completed trials are briefly described, and modes of action for each drug are discussed. The authors also talk about the problems with injected drugs and why people have a hard time adhering to them, but if you're all too familiar with those topics, just skip down to the section entitled, "What are the emerging options for oral therapy in MS?"