[jgfoot]

Perhaps darcs' most prominent user base is the guys who work on GHC, the Glasgow Haskell Compiler. They still use it, but have not been completely happy: http://hackage.haskell.org/trac/ghc/wiki/DarcsEvaluation

[Chirono]

Actually, GHC has been using GIT for about a year now. There was a lot of discussion but darcs has (mostly) been dropped. There are a few libraries that are still darcs-controlled but generally because nobody has got round to migrating them I think...