The short version is that they let you deploy "Arrows" over the network. The long version makes reference to Lamport and touches on the use of theorem provers in their system.This makes life easier :) I wanted to do something similar via JS (Flapjax) & Erlang awhile back, but wasn't convinced of the benefit for web apps, and for straight out parallel systems as part of my parallel browser project. The verification side looks interesting - someone from NEU (?) was looking at this a year or two back, and I'm not sure what happened.
Lucid-Synchrone may also be of interest as a functional, distributed, (parallel?) reactive system. Walid Taha et al's E-FRP with priorities were aimed at a more RT approach, though I'm watching for it going down the parallel/distributed lines soon. The field has gone a long ways since the prototypes and hints by the Haskell and Scheme communities.
Back to searching and speeding up the web.. hopefully put together my thoughts on socializing it later :) In other news, it looks like the object capability folks are preaching on the ECMAScript list nowadays. Sadly, I'm swayed - though not as a security mechanism. Both the dropping of ES4 and modern focus on obj caps are also topics for another day :)