I really like both the Julia and R communities, so always glad to see good interoperability between them!
It's also good to see the communities come up with different approaches to the same problem. I'm not an R user, but R Markdown is really great, and I'm glad that someone put forward such a strong candidate. Similarly, much as I love Jupyter, I'm really glad that projects like Pluto.jl and RStudio exist to expand what's possible.