Output other than PDF

[Brett Duncan]

I'm using the Mac OS X binary of Lilypond (2.6.1) and loving it. But how 
do I get the output as something other than PDF? Specifically, I want 
PNG, but PS would also be useful. Obviously I can't use the GUI to 
achieve this, so I'm assuming (hoping) that there is a way to invoke 
Lilypond via the command line in Terminal that will let me specify the 
output format I want. Can anyone clear this up for me?

TIA,

Brett Duncan