I'm trying to use org-mode to reproduce the HTML slide show made with knitr demonstrated at http://goo.gl/bOJJo .  The following single code block works

#+BEGIN_SRC R :results output html
  library(googleVis)
  G <- gvisGeoChart(Exports, "Country", "Profit", options = list(width = 250, 
      height = 120))
  print(G)
#+END_SRC

and wraps it in the needed HTML block, but if I set :session on the block the "R>" prompt is included in the output. If i set a file level session property it works fine, but if on a single block inserts the prompt.  I was expecting these would behave identically.

Is this the expected behavior?

Greg