Peak Oil is real. It's documented. It happened to the US in the early 1970's and caused lots of problems. We started to import, but there won't be anywhere to import from when we hit world-wide peak oil. Pretty scary stuff.
There's a great lecture you can download that explains it at ::
http://www.radio4all.net/index.php?op=program-info&program_id=7365&nav=&Richard Heinberg, who writes about peak oil, explains the phenomenon, documents why it's real, talks about what it means and talks about alternative sources.