The episode i saw, there was a speaker in the end saying, that the next episode (13) would be the season finale. But you can read more at:
http://www.tvtome.com/tvtome/servlet/ShowForumPage/showid-23557/threadid-166372/
To the best of my knowledge, it should air on monday. Just like the other episodes.
I Just checked, and Monday it is.
http://www.tvtome.com/tvtome/servlet/GuidePageServlet/showid-23557/epid-307376/
I found one, its the top 10 theories of 2002, they are mostly about the attacks 9/11, and are quite funny reading. :D
http://www.alternet.org/story/14873