I haven't tried it yet but you can use clojurescript functions from javascript. The more common direction of interop (from using js from clojurescript) is quite nice and it looks like the opposite is also quite nice.

Best writeup about that I've seen so far is here: http://lukevanderhart.com/2011/09/30/using-javascript-and-cl... (in the exporting section)

I'm not sure if there are any implications I'm not aware of that would make it less useful to use core.async from js land.