It will air in October, don't know the exact date but its definitely airing on October 2011
Season 4 airs in 2012
YES - the 4th season of Merlin will air in 2011-2012
2012
December 10,2012
October 26, 2010 it was announced Season 4 has been commissioned. It will be a 10 episode season. In the related links section below there is a link to the article.
No
March 15, 1989.
Not soon enough.
yes Merlin season 3 is out
I'm not sure when it begins airing in the US but I know that you can start watching season 3 on casttv.com.
It will come out next year 2012.
Amazon.com At your local retail store.