Don't know if this has become public knowledge yet (it wasn't in the MacWorld Expo keynote), but Apple have just released a public beta X11 package based on Xfree86. http://www.apple.com/macosx/x11/download/ Apparently there are some issues with existing installations of XDarwin and OroborosX, but if you have a clean slate and are looking to move to the X11 version of R, this could be the ticket. Joe Costa