The USGS will not conduct their formal estimate until 2007-8, and we have been drilling wells in this for the past 6 years. Maybe someday we will 'run out', but we are not there yet.
As for Titan, methane origin is somewhat explained here. No critters are believed to be involved, but then, there are no producing oil wells on Titan, either. (Longer chain hydrocarbons are believed to not be present.)
Holy cow. That's a lot of gasoline.
Maybe I should buy a Hummer while everyone else is selling them...
L
That's awfully big. Are you sure those numbers are correct, because that's bigger than the largest oil field in the world, which is in Saudi?