hal daume, who also wrote "yet another haskell tutorial", is an NLP researcher, and uses O'Caml, Haskell and C successfully: http://www.umiacs.umd.edu/~hal/software.html

andrew mccallum, one of the originators of conditional random fields and also an NLPer, has recently been using scala: http://code.google.com/p/factorie/