The company I work at uses Java as its 'main' language. In the past year my team has been increasingly using Scala for new development. One of the most useful features of Scala is the functional treatment of collections. Most of the programming we do (that everyone does?) is really just manipulation of collections, so being able to map/filter/reduce/group collections in a couple of lines of code, rather than the verbose Java equivalent, is a big win.
I don't want to weigh in on the general 'are functional languages' better debate (as I don't have enough experience of them), just wanted to share that as a data point.