In Snow Leopard by default it loaded 32-bit kernel:
\r
Darwin blah.blah 10.4.0 Darwin Kernel Version 10.4.0: Fri Apr 23 18:28:53 PDT 2010; root:xnu-1504.7.4~1/RELEASE_I386 i386 i386
\r
That does not prevent to work successfully both 32 and 64-bit applications. It is x never experimented, but I think that everything will work.