In RStudio 1.1, you can use RStudio as a Python REPL. There's not support for it specifically, but since we now have a terminal that you can send lines to, and you can run Python in that terminal, it's surprisingly usable.
(h/t @GaryR for screenshot)
It's never been our goal to make RStudio a fully multilingual IDE, but we've improved Python support in every release (check out the integration with the reticulate package if you haven't already), and have plans for more Python support in 1.2. Stay tuned!