How to start editor from within R.

By using the menu command, I am able to open the built in editor  
without tieing up the command line the way that edit() does.  Is  
there a way to do this from within R?

Using the built-in editor? I don't think so - there may be a back  
door using the 'open' mechanism, but nothing directly.

  Also, is there a command to start the X11 server from within R or  
is this also only accessible from the menu?

Pretty much the same answer, you could use something like system 
("open /Application/Utilities/X11.app"), but I guess that's not what  
you meant ;).

Cheers,
Simon