I think Haskell has been growing a lot fueled by having a really great base language finally getting a pretty comprehensive standard library. This was a highly intentional group effort that began probably 10 years ago and pushed the Haskell libraries to a level of maturity.

I can't truly claim this has driven the adoption of other languages, but Haskell's (or pick some language from the ML roulette) influence on Clojure and Scala is undeniable. Clojure's commitment to immutability pales in comparison to Haskell's, while the latter demonstrates the advantages of such programming in spades. Scala's type system is a novel extension of the HM system which forms the basis of Haskell's.

So am I claiming that the increased availability and "practicality" of Haskell has driven a renaissance in functional programming?

Sort of, yes, but I don't feel it's the core underlying cause. More a symptom in its own right. These ideas are the leading edge of programming language research. They're smart to learn and to integrate into our next generation of tools. This evidence has long resounded from finding them at the center of the "Holy Trinity" of category theory, logic, and type theory. It's "practical" significance is still growing, however.