I am hoping one of you with more experience with the quirks of my car (2001 Boxster 2.7 liter) can speed up my diagnostic process...
I just bought this car and have been working my way through several little gremlins.
Last time I drove it (about 8 miles)  it started leaking oil and smoking severely and it looked to be coming from the passenger's side (American) of the engine (and smoked out the side cooling vent/gill) and sprayed enough that some oil onto the back of the bumper pads.
I pulled both  covers off the engine and did not see any oil on the "top" of the engine like some posts I have read.  
I crawled underneath and it does appear that the leak is coming from the front passenger's side somewhat close to the alternator.
I started it tonight and it definitely looks like the smoke is coming from the oil dripping on that right-hand catalytic converter.  There was a big drop of oil just hanging onto the bottom of the cat.
I still can't really tell where the leak is.  (I also noted the oil pan is oily but that doesn't seem to be the smoking problem  - I plan to save that problem for later unless you tell me otherwise).  I think I need to raise the car some more because I can barely fit underneath it (plus there are some hot parts about 1 inch from my face.)
While running, I did remove the oil filler cap in the rear trunk.  It wasn't really "suctioned" on there (easier than taking the top off a pickle jar) but I did hear a vacuum release when I opened it.  The engine also started to "throb" with the engine rpm's moving up and down a bit instead of staying at a steady idle  (I didn't read the tach so I can't tell you the range.).  I put my hand over the oil filler tube/funnel and it is definitely drawing a vacuum there.  When I put the cap back on, it returned to normal idle.
I am hoping one of you guys will tell me what I want to hear...e.g., - this is easy and you'll be driving again in no time.
Could it be the Air/Oil Separator?
Could it be a Spark plug seal?  (i still haven't even found the spark plugs but I did buy the Bentley book so I know I can find them.)
Please let me know your thoughts even if you are going to tell me something rough...
Thanks!!!