[plt-scheme] Universal Binaries?

Am I able to build (or am I building?) universal binaries when I build 
MzScheme/MrEd apps?

Eg. When I say "mzc --exe foo foo.scm && mzc --exe-dir foo-dir foo" , is 
that bundling up a universal binary? What about "Build Application" 
(or... whatever its called) in DrScheme? If I create a MrEd executable 
for distribution, can that application be executed on either a PPC or 
Intel Mac?

Cheers,
Matt