Here is the first link that came up to the story but I was unable to get the page to load (may be too busy):
http://news.bbc.co.uk/1/hi/world/mid...st/7657066.stm

Iran report says U.S. plane violated Iran's airspace
Tue Oct 7, 2008 9:34am EDT
TEHRAN (Reuters) - An Iranian news agency said on Tuesday that a U.S. military aircraft had unintentionally violated Iranian airspace and been forced to land in Iran, but later allowed to leave.

http://www.reuters.com/article/newsO...4964ZV20081007


A story printed 12 minutes ago, linked below, reports that the Pentagon is denying the claim that a U.S. Plane was forced to land in Iran.
http://www.reuters.com/article/newsO...49653N20081007

WASHINGTON (Reuters) - The Pentagon denied on Tuesday an Iranian news report that a U.S. military aircraft had violated Iranian territory and had been forced to land in Iran, saying all American planes were accounted for.
I think the Pentagon's denial is accurate in that it was not a "military aircraft".