Post #21 in this thread( read the article as well if you haven't already seen this) gives a good background of the islamic mindset of Iran's leader:
http://www.freerepublic.com/focus/f-news/1542163/posts
From the post:
"...the Mahdi as he exists in the minds of many of the 1.3 billion Muslims worldwide.
1. The Mahdi is Islams primary messiah figure.
15. He will cause Islam to be the only religion practiced on the earth.
21. He will be loved by all the people of the earth.