Updated 080908: The root server operators have a map of their own that I recommend. There is also an XML version of the data so anyone can make a map of their own.
I still meet people that think the following is true:
There are 13 root servers in the world
The A-root is the main DNS server
Almost all root servers are located in the USA
All of those statements, and similar, are just completely wrong. You can find more information about the organisations that run the root servers here, and find a map I have done at Google here. Updated: Got information about a server existing on Fiji, and found on the homepage of Autonomica [I] that servers also existed in Kathmandu and Luleå. If you know more servers missing, just let me know (for example via a comment to this blog).
Updated 071123: Edna Samudio gave me information that F has a server in Panama since July 17, 2007. Information about the server can be found here.