They're working on the South Park RPG, then there's J.E. Sawyers new project (of which nothing is known, but a vague tweet about stealth gameplay (remember reading about it somewhere) and hints towards discussions with Eidos Montreal and Square Enix, and these may not even mean anything towards their future endeavors), and then there is the Wheel of Time RPG which may or may not happen, and which Obsidian is allegedly only helping with and not really "developing".
Only the South Park RPG is announced.
Someone with better knowledge, feel free to correct me if there is something to correct.