There's OO programming and generic programming which are popular in computational finance. The Functional Programming model complements them because it focuses on all aspects of (mathematical) functions and their implementation in a compiler. It allows developers to do things much more easily than with OOP and GP.
In C++, you can use FP in the Boost libraries Function, signal2 and Bind.
I would say that FP model will become more important. For example, we have implemented many of the Gamma GOF and POSA patterns using FP methods. It's like a breath of fresh air