Hi,
My Boxster had the exact same appearance for the oil leak. After tear down, I believe the leak was coming from the IMS flange. It was the old single o-ring type seal. The IMSB was totally fine (even though I still replaced it). I replaced the RMS, but it too looked fine.
See pics here:
http://986forum.com/forums/performance-technical-chat/45685-oil-leak-pulling-trans-change-rms-ims-clutch-etc.html