Nissan Altima

I have a 1995 Nissan Altima, roughly 140k miles. Recently, I've discovered an oil leak that has apparently been there for a while. Here is a picture: (if anyone would like a full-size pic, I can provide that)

There is a lot of oil residue (see pic), so I'm not 100% sure of where the leak is coming from, but I would say it is more than likley coming from the distributor. After speaking with a local mechanic, he said that all I would need to do is take the distributor cap off & spray with brake/carburetor cleaner and that would take care of it. Can anyone confirm/explain this better?
January 18, 2007.

Double check the valve cover gasket-if its not it- 99.9 its the distributor shaft O-ring-need to remove distributor for replacement.

HTH-Good LUck!

Jan 19, 2007.