Peak Oil definition from Wikipedia:
The Hubbert peak theory, also known as peak oil, is an influential theory concerning the long-term rate of conventional oil (and other fossil fuel) extraction and depletion. It predicts that future world oil production will reach a peak and then rapidly decline. The actual peak year will only be known after it has passed.
I know it could be just a PR effort to make it look like they care about declining energy reserves. And looking around the site they don't seem to worry about the environmental impacts of oil use, they seem more concerned that because oil consumption is so high, they can't find enough oil fast enough for everyone's needs. This means they want you to reduce your consumption so their business lasts longer.
Although some fruit loop (they may, in fact, be called geniuses in the future though) geologists have a theory that deep in the Earth's crust there are rock types that are secreting oil and gas. Time will tell I suppose...