Language Details: Lisp

Lisp is a family of computer programming languages with a long history and a distinctive, fully parenthesized Polish prefix notation.

Lisp article on Wikipedia
Code Jam 2012 Contestants using Lisp
Qualification Round
Used in 77 solutions by 24 contestants:
Round 1A
Used in 6 solutions by 4 contestants:
Round 1B
Used in 7 solutions by 4 contestants:
Round 1C
Used in 17 solutions by 8 contestants:
Round 2
Used in 3 solutions by 1 contestants:

Submission Origin

Japan (7 contestants)
United States (6 contestants)
China (2 contestants)
Germany (2 contestants)
Russia (2 contestants)
Australia (1 contestant)
Canada (1 contestant)
Czech Republic (1 contestant)
India (1 contestant)
Poland (1 contestant)
Singapore (1 contestant)
Switzerland (1 contestant)