[OS X Emacs] 1.5 and "open -a"

[C. R. Oldham]

Greetings,

Didn't "open -a Aquamacs\ Emacs" used to open a new frame with a file  
if Emacs was already running?  Now it seems to open a brand new Emacs  
instance.  Can we get the old behavior back, or is there a variable to  
set?

--cro