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 2010 Contestants using Lisp
Qualification Round
Used in 66 solutions by 19 contestants:
Round 1A
Used in 5 solutions by 2 contestants:
Round 1B
Used in 21 solutions by 7 contestants:
Round 1C
Used in 7 solutions by 3 contestants:
Round 2
Used in 5 solutions by 4 contestants:

Submission Origin

United States (5 contestants)
Russia (3 contestants)
Chile (2 contestants)
Spain (2 contestants)
Australia (1 contestant)
Canada (1 contestant)
France (1 contestant)
Germany (1 contestant)
Hungary (1 contestant)
Japan (1 contestant)
United Kingdom (1 contestant)