Language Details: F#

F# is a strongly-typed, functional-first programming language for writing simple code to solve complex problems.

Official website (see also: Wikipedia article)
Code Jam 2012 Contestants using F#
Qualification Round
Used in 58 solutions by 18 contestants:
Round 1A
Used in 13 solutions by 7 contestants:
Round 1B
Used in 6 solutions by 3 contestants:
Round 1C
Used in 17 solutions by 8 contestants:
Round 2
Used in 1 solutions by 1 contestants:

Submission Origin

United States (4 contestants)
United Kingdom (3 contestants)
Germany (2 contestants)
Russia (2 contestants)
Ukraine (2 contestants)
... (1 contestant)
Australia (1 contestant)
China (1 contestant)
Czech Republic (1 contestant)
France (1 contestant)
Greece (1 contestant)
Hungary (1 contestant)
Japan (1 contestant)
Kazakhstan (1 contestant)