Language Details: Clojure

Clojure is a dialect of Lisp that targets the Java Virtual Machine.

Official website (see also: Wikipedia article)
Code Jam 2012 Contestants using Clojure
Qualification Round
Used in 81 solutions by 30 contestants:
Round 1A
Used in 9 solutions by 5 contestants:
Round 1B
Used in 6 solutions by 3 contestants:
Round 1C
Used in 5 solutions by 3 contestants:

Submission Origin

United States (6 contestants)
Germany (4 contestants)
Canada (3 contestants)
Brazil (2 contestants)
Japan (2 contestants)
Australia (1 contestant)
Austria (1 contestant)
Belarus (1 contestant)
Finland (1 contestant)
France (1 contestant)
Israel (1 contestant)
Mexico (1 contestant)
Norway (1 contestant)
Russia (1 contestant)
South Africa (1 contestant)
Spain (1 contestant)
Switzerland (1 contestant)
United Kingdom (1 contestant)