What is Haskell?

I just heard about this functional programming language named Haskell on this Ruby on Rails Podcast interview with Jim Vanderburgh

• http://www.haskell.org/haskellwiki/Haskell
• http://www.haskell.org/haskellwiki/Why_Haskell_Matters

This article was originally posted by Mike Franks on the UCLA Programmers Wiki.