I had few oil drops leak on my car too. It was the rear main seal. I was worried that it might came from IMS seal but it was the RMS that leaked on mine. It was an expensive repair (seal is under $20 but you have to remove the transmission to get to the seal). I replaced all the parts that was on the way too so my total bill was close to $3K (RMS, IMS, clutch, clutch/brake fluid, trans fluid and AOS).
Hopefully yours is coming from different spot (not RMS or IMS) so it should be cheaper to repair.
You can check under the car on where the wet spots are. Mine was from the area when engine connects to transmission.
You can see the wet spot from picture 1-4:
http://s1097.photobucket.com/albums/g344/laphan/Boxster/
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