Any ideas where this may be coming from? (2005 997 C2S)

 

That looks like seepage migrating along the threads of the bolts used to hold the case halves together, which is often misdiagnosed as an RMS leak. Don't worry, it is easily remedied by removing each bolt, cleaning the threads (brake cleaner works well), putting some oil resistant RTV/silicone on the threads, re-installing, and tightening to the proper torque, then moving on to the next one, doing only one at a time so the case doesn't come apart. Do all the bolts on both sides, but again, one at a time - remove, clean, apply sealant, reinstall, torque, move onto the next one. Ideally, do it at the next oil change after you've drained the oil, and let the sealant setup for 24 hours before refilling the engine with the new oil - this will allow the sealant to cure better. Clean both the bolt threads and the bolt holes in the engine.

I had the same issue and my leak was bad enough that after a high RPM spirited drive, it would actually create a small puddle on the floor, but not after a normal drive. It's been bone dry for a few years now after I did this repair procedure.

 

Thank you Petza - I'll take a look at doing this on next oil change.

 

Good deal. Here's what mine looked like that was fixed by my process description below.