Are you referring to the various databinding frameworks? So far, I've been somewhat skeptical of those--I worry they make too many assumptions and take away too much fine-grained control.
The amount of people I know who use functional frameworks (say Underscore) to build things but don't really know much about functional programming is astonishing. To be fair, a lot of frameworks that espouse "functional programming" do so just because it's popular and really push imperative concepts instead so it's easy to be confused on the "right way".
I love Underscore (and Haskell), but I wouldn't consider Underscore an FRP framework at all. It's functional, yes, in the sense that it provides some of the most common FP operations like map, filter, etc, using lambdas. But I don't see the reactive part. Maybe there's some kind of reactive feature tucked away in Underscore's rather large feature set, but I haven't seen it, and it's certainly not core to the library.
We are able to subvert WPF databinding mechanisms to allow bindings to expressions as well as functions. The act of binding itself is still very imperative (and so, not very FRP-ish), but beyond that the programming styles are quite similar.
